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path: root/drivers/clk/samsung/clk-exynos850.c
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2024-03-26clk: samsung: exynos850: Add CMU_CPUCL0 and CMU_CPUCL1Sam Protsenko1-1/+439
Implement support for CPU clock management units: - CMU_CPUCL0: clocks for cluster 0: 4 x Cortex-A55 (cpu0..cpu3) - CMU_CPUCL1: clocks for cluster 1: 4 x Cortex-A55 (cpu4..cpu7) CPU PLLs are generating main CPU clocks for each cluster, and there are alternate ("switch") clocks that can be used temporarily while re-configuring the PLL for a new rate. ACLK, ATCLK, PCLKDBG and PERIPHCLK clocks are driving corresponding buses. CLK_CLUSTERx_SCLK are actual leaf CPU clocks and should be used to change CPU rates. Also some CoreSight clocks can be derived from DBG_USER (debug clock). PLL table was extracted from ECT table. ECT stands for "Exynos Characteristic Table", it's a Samsung specific binary data populated by BL2 bootloader in RAM at 0x90000000 address, containing PLL tables for various CMUs and other hardware specific information. The particular PLL type used in CMU_CPUCL0 and CMU_CPUCL1 (pll0822x) is an integer PLL with middle FVCO. The equation to calculate its output rate is: fout = fin * M / (P*2^S) where: fin = 26 MHz (OSCCLK frequency) M = 64..1023 P = 1..63 S = 0..6 The PLL table tries to keep "P" value low to reduce the locking time, which for pll0822x is "t = P * 150" (in OSCCLK cycles). Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Link: https://lore.kernel.org/r/20240301015118.30072-2-semen.protsenko@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2024-02-01clk: samsung: exynos850: Propagate SPI IPCLK rate changeSam Protsenko1-16/+17
When SPI transfer is being prepared, the spi-s3c64xx driver will call clk_set_rate() to change the rate of SPI source clock (IPCLK). But IPCLK is a gate (leaf) clock, so it must propagate the rate change up the clock tree, so that corresponding DIV clocks can actually change their divider values. Add CLK_SET_RATE_PARENT flag to corresponding clocks for all SPI instances in Exynos850 (spi_0, spi_1 and spi_2) to make it possible. This change involves next clocks: usi_spi_0: Clock Block Div range -------------------------------------------- gout_spi0_ipclk CMU_PERI - dout_peri_spi0 CMU_PERI /1..32 mout_peri_spi_user CMU_PERI - dout_peri_ip CMU_TOP /1..16 usi_cmgp0: Clock Block Div range -------------------------------------------- gout_cmgp_usi0_ipclk CMU_CMGP - dout_cmgp_usi0 CMU_CMGP /1..32 mout_cmgp_usi0 CMU_CMGP - gout_clkcmu_cmgp_bus CMU_APM - dout_apm_bus CMU_APM /1..8 usi_cmgp1: Clock Block Div range -------------------------------------------- gout_cmgp_usi1_ipclk CMU_CMGP - dout_cmgp_usi1 CMU_CMGP /1..32 mout_cmgp_usi1 CMU_CMGP - gout_clkcmu_cmgp_bus CMU_APM - dout_apm_bus CMU_APM /1..8 With input clock of 400 MHz, this scheme provides next IPCLK rate range, for each SPI block: SPI0: 781 kHz ... 400 MHz SPI1/2: 1.6 MHz ... 400 MHz Accounting for internal /4 divider in SPI blocks, and because the max SPI frequency is limited at 50 MHz, it gives us next SPI SCK rates: SPI0: 200 kHz ... 49.9 MHz SPI1/2: 400 kHz ... 49.9 MHz Which should cover all possible applications of SPI bus. Of course, setting SPI frequency to values as low as 500 kHz will also affect the common bus dividers (dout_apm_bus or dout_peri_ip), which in turn effectively lowers the rates for all leaf bus clocks derived from those dividers, like HSI2C and I3C clocks. But at least it gives the board designer a choice, whether to keep all clocks (SPI/HSI2C/I3C) at high frequencies, or make all those clocks have lower frequencies. Not propagating the rate change to those common dividers would limit this choice to "only high frequencies are allowed for SPI/HSI2C/I3C" option, making the common dividers useless. This decision follows the "Worse is better" approach, relying on the users/engineers to know the system internals when working with such low-level features, instead of trying to account for all possible use-cases. Fixes: 7dd05578198b ("clk: samsung: Introduce Exynos850 clock driver") Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org> Link: https://lore.kernel.org/r/20240125013858.3986-2-semen.protsenko@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2024-01-23clk: samsung: exynos850: Add PDMA clocksSam Protsenko1-1/+9
Add Peripheral DMA (PDMA) clocks in CMU_CORE controller: - PDMA_ACLK: clock for PDMA0 (regular DMA) - SPDMA_ACLK: clock for PDMA1 (secure DMA) Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Link: https://lore.kernel.org/r/20240120012948.8836-4-semen.protsenko@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2023-08-31Merge branches 'clk-imx', 'clk-samsung', 'clk-annotate', 'clk-marvell' and ↵Stephen Boyd1-11/+24
'clk-lmk' into clk-next - Add __counted_by to struct clk_hw_onecell_data and struct spmi_pmic_div_clk_cc - Remove non-OF mmp clk drivers - Move number of clks from DT headers to drivers * clk-imx: clk: imx: pll14xx: dynamically configure PLL for 393216000/361267200Hz clk: imx: pll14xx: align pdiv with reference manual clk: imx: composite-8m: fix clock pauses when set_rate would be a no-op clk: imx25: make __mx25_clocks_init return void clk: imx25: print silicon revision during init dt-bindings: clocks: imx8mp: make sai4 a dummy clock clk: imx8mp: fix sai4 clock clk: imx: imx8ulp: update SPLL2 type clk: imx: pllv4: Fix SPLL2 MULT range clk: imx: imx8: add audio clock mux driver dt-bindings: clock: fsl,imx8-acm: Add audio clock mux support clk: imx: clk-imx8qxp-lpcg: Convert to devm_platform_ioremap_resource() clk: imx: clk-gpr-mux: Simplify .determine_rate() clk: imx: Add 519.75MHz frequency support for imx9 pll clk: imx93: Add PDM IPG clk dt-bindings: clock: imx93: Add PDM IPG clk * clk-samsung: dt-bindings: clock: samsung: remove define with number of clocks clk: samsung: exynoautov9: do not define number of clocks in bindings clk: samsung: exynos850: do not define number of clocks in bindings clk: samsung: exynos7885: do not define number of clocks in bindings clk: samsung: exynos5433: do not define number of clocks in bindings clk: samsung: exynos5420: do not define number of clocks in bindings clk: samsung: exynos5410: do not define number of clocks in bindings clk: samsung: exynos5260: do not define number of clocks in bindings clk: samsung: exynos5250: do not define number of clocks in bindings clk: samsung: exynos4: do not define number of clocks in bindings clk: samsung: exynos3250: do not define number of clocks in bindings * clk-annotate: clk: qcom: clk-spmi-pmic-div: Annotate struct spmi_pmic_div_clk_cc with __counted_by clk: Annotate struct clk_hw_onecell_data with __counted_by * clk-marvell: clk: pxa910: Move number of clocks to driver source clk: pxa1928: Move number of clocks to driver source clk: pxa168: Move number of clocks to driver source clk: mmp2: Move number of clocks to driver source clk: mmp: Remove old non-OF clock drivers * clk-lmk: clk: lmk04832: Support using PLL1_LD as SPI readback pin clk: lmk04832: Don't disable vco clock on probe fail clk: lmk04832: Set missing parent_names for output clocks
2023-08-15clk: samsung: exynos850: do not define number of clocks in bindingsKrzysztof Kozlowski1-11/+24
Number of clocks supported by Linux drivers might vary - sometimes we add new clocks, not exposed previously. Therefore these numbers of clocks should not be in the bindings, as that prevents changing them. Define number of clocks per each clock controller inside the driver directly. Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org> Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com> Link: https://lore.kernel.org/r/20230808082738.122804-10-krzysztof.kozlowski@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2023-07-19clk: Explicitly include correct DT includesRob Herring1-1/+0
The DT of_device.h and of_platform.h date back to the separate of_platform_bus_type before it as merged into the regular platform bus. As part of that merge prepping Arm DT support 13 years ago, they "temporarily" include each other. They also include platform_device.h and of.h. As a result, there's a pretty much random mix of those include files used throughout the tree. In order to detangle these headers and replace the implicit includes with struct declarations, users need to explicitly include the correct includes. Acked-by: Dinh Nguyen <dinguyen@kernel.org> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> # samsung Acked-by: Heiko Stuebner <heiko@sntech.de> #rockchip Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Acked-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # versaclock5 Signed-off-by: Rob Herring <robh@kernel.org> Link: https://lore.kernel.org/r/20230718143156.1066339-1-robh@kernel.org Acked-by: Abel Vesa <abel.vesa@linaro.org> #imx Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2023-03-13clk: samsung: exynos850: Make PMU_ALIVE_PCLK criticalSam Protsenko1-1/+1
PMU_ALIVE_PCLK is needed for PMU registers access, and it must be always running, as not only the kernel accesses PMU registers. Make it critical to ensure that. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Link: https://lore.kernel.org/r/20230308233822.31180-5-semen.protsenko@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2023-03-06clk: samsung: exynos850: Add AUD and HSI main gate clocksSam Protsenko1-0/+19
Add main gate clocks for controlling AUD and HSI CMUs: - gout_aud_cmu_aud_pclk - gout_hsi_cmu_hsi_pclk Those clocks were marked as CLK_IGNORE_UNUSED, as system hangs on boot otherwise. While at it, add missing PPMU (Performance Profiling Monitor Unit) clocks for CMU_HSI. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Reviewed-by: Chanho Park <chanho61.park@samsung.com> Link: https://lore.kernel.org/r/20230223042133.26551-6-semen.protsenko@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2023-03-06clk: samsung: exynos850: Implement CMU_G3D domainSam Protsenko1-0/+120
CMU_G3D clock domain provides clocks for Mali-G52 GPU and bus clocks for BLK_G3D. This patch adds next clocks: - bus clocks in CMU_TOP for CMU_G3D - all internal CMU_G3D clocks - leaf clocks for GPU, TZPC (TrustZone Protection Controller) and SysReg G3D_CMU_G3D clock was marked as CLK_IGNORE_UNUSED, as system hangs on boot otherwise. Reviewed-by: Chanho Park <chanho61.park@samsung.com> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Link: https://lore.kernel.org/r/20230223042133.26551-5-semen.protsenko@linaro.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
2022-08-23clk: samsung: exynos850: Implement CMU_MFCMSCL domainSam Protsenko1-0/+176
CMU_MFCMSCL clock domain provides clocks for MFC (Multi-Format Codec), JPEG Codec and Scaler IP-cores. According to Exynos850 TRM, CMU_MFCMSCL generates MFC, M2M, MCSC and JPEG clocks for BLK_MFCMSCL. This patch adds next clocks: - bus clocks in CMU_TOP for CMU_MFCMSCL - all internal CMU_MFCMSCL clocks - leaf clocks for MFCMSCL, TZPC (TrustZone Protection Controller), JPEG codec, M2M (Memory-to-Memory), MCSC (Multi-Channel Scaler), MFC (Multi-Format Codec), PPMU (Platform Performance Monitoring Unit), SysMMU and SysReg MFCMSCL related gate clocks in CMU_TOP were marked as CLK_IS_CRITICAL, because: 1. All of those have to be enabled in order to read /sys/kernel/debug/clk/clk_summary file 2. When some user driver (e.g. exynos-sysmmu) disables some derived leaf clock, it can lead to CMU_TOP clocks disable, which then makes the system hang. To prevent that, the CLK_IS_CRITICAL flag is used, as CLK_IGNORE_UNUSED is not enough. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Link: https://lore.kernel.org/r/20220809113323.29965-8-semen.protsenko@linaro.org
2022-08-23clk: samsung: exynos850: Implement CMU_IS domainSam Protsenko1-0/+199
CMU_IS clock domain provides clocks for IS IP-core (Image Signal Processing Subsystem). According to Exynos850 TRM, CMU_IS generates CSIS, IPP, ITP, VRA and GDC clocks for BLK_IS. This patch adds next clocks: - bus clocks in CMU_TOP needed for CMU_IS - all internal CMU_IS clocks - leaf clocks for IS IP-core, CSIS (Camera Serial Interface Slave), D_TZPC (TrustZone Protection Controller), CSIS DMA, GDC (Geometric Distortion Correction), IPP (Image Preprocessing Processing core), ITP (Image Texture Processing core), MCSC (Multi-Channel Scaler), VRA (Visual Recognition Accelerator), PPMU (Platform Performance Monitoring Unit), SysMMU and SysReg IS related gate clocks in CMU_TOP were marked as CLK_IS_CRITICAL, because: 1. All of those have to be enabled in order to read /sys/kernel/debug/clk/clk_summary file 2. When some user driver (e.g. exynos-sysmmu) disables some derived leaf clock, it can lead to CMU_TOP clocks disable, which then makes the system hang. To prevent that, the CLK_IS_CRITICAL flag is used, as CLK_IGNORE_UNUSED is not enough. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Link: https://lore.kernel.org/r/20220809113323.29965-7-semen.protsenko@linaro.org
2022-08-23clk: samsung: exynos850: Implement CMU_AUD domainSam Protsenko1-0/+302
CMU_AUD clock domain provides clocks for ABOX IP-core (audio subsystem). According to Exynos850 TRM, CMU_AUD generates Cortex-A32 clock, bus clock and audio clocks for BLK_AUD. This patch adds next clocks: - bus clocks in CMU_TOP needed for CMU_AUD - all internal CMU_AUD clocks - leaf clocks for Cortex-A32, Speedy FM, UAIF0..UAIF6 (Unified Audio Interface), CNT (counter), ABOX IP-core, ASB (Asynchronous Bridge), DAP (Debug Access Port), I2S Codec MCLK, D_TZPC (TrustZone Protection Controller), GPIO, PPMU (Platform Performance Monitoring Unit), SysMMU, SysReg and WDT ABOX clock was marked as CLK_IGNORE_UNUSED, as system hangs on boot otherwise. Once ABOX driver is implemented, maybe it can be handled there instead. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Link: https://lore.kernel.org/r/20220809113323.29965-6-semen.protsenko@linaro.org
2022-08-23clk: samsung: exynos850: Style fixesSam Protsenko1-3/+2
Fix some typos in comments and do small coding style improvements. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Link: https://lore.kernel.org/r/20220809113323.29965-5-semen.protsenko@linaro.org
2021-12-20clk: samsung: Make exynos850_register_cmu sharedDavid Virag1-84/+4
Rename exynos850_register_cmu to exynos_arm64_register_cmu and move it to a new file called "clk-exynos-arm64.c". This should have no functional changes, but it will allow this code to be shared between other arm64 Exynos SoCs, like the Exynos7885 and possibly ExynosAuto V9. Signed-off-by: David Virag <virag.david003@gmail.com> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Link: https://lore.kernel.org/r/20211206153124.427102-5-virag.david003@gmail.com
2021-12-20clk: samsung: exynos850: Add missing sysreg clocksSam Protsenko1-0/+29
System Register is used to configure system behavior, like USI protocol, etc. SYSREG clocks should be provided to corresponding syscon nodes, to make it possible to modify SYSREG registers. While at it, add also missing PMU and GPIO clocks, which looks necessary and might be needed for corresponding Exynos850 features soon. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Link: https://lore.kernel.org/r/20211217161549.24836-3-semen.protsenko@linaro.org
2021-11-23clk: samsung: exynos850: Register clocks earlySam Protsenko1-21/+49
Some clocks must be registered before init calls. For example MCT clock (from CMU_PERI) is needed for MCT timer driver, which is registered with TIMER_OF_DECLARE(). By the time we get to core_initcall() used for clk-exynos850 platform driver init, it's already too late. Inability to get "mct" clock in MCT driver leads to kernel panic, as functions registered with *_OF_DECLARE() can't do deferred calls. MCT timer driver can't be fixed either, as it's acting as a clock source and it's essential to register it in start_kernel() -> time_init(). Let's register CMU_PERI clocks early, using CLK_OF_DECLARE(). CMU_TOP generates clocks needed for CMU_PERI, but it's already registered early. While at it, let's cleanup the code a bit, by extracting everything related to CMU initialization and registration to the separate function. Similar issue was discussed at [1] and addressed in commit 1f7db7bbf031 ("clk: renesas: cpg-mssr: Add early clock support"), as well as in drivers/clk/mediatek/clk-mt2712.c. [1] https://patchwork.kernel.org/project/linux-renesas-soc/patch/20180829132954.64862-2-chris.brandt@renesas.com/ Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Link: https://lore.kernel.org/r/20211122144206.23134-1-semen.protsenko@linaro.org
2021-11-22clk: samsung: exynos850: Keep some crucial clocks runningSam Protsenko1-6/+13
Some clocks shouldn't be automatically disabled in clk_disable_unused(), otherwise kernel hangs. Mark those clocks with: - CLK_IS_CRITICAL flag, when there won't be any consumers for that clock, but system can't function when it's gated - CLK_IGNORE_UNUSED flag, when consumer driver will be probably added later That makes it possible to run the kernel without passing the "clk_ignore_unused" param. Next clocks were modified: - "gout_dpu_cmu_dpu_pclk": CLK_IGNORE_UNUSED Will be enabled later in DSIM driver (Display Serial Interface Master). - "gout_gpio_peri_pclk": CLK_IGNORE_UNUSED "gout_gpio_cmgp_pclk": CLK_IGNORE_UNUSED "gout_gpio_hsi_pclk": CLK_IGNORE_UNUSED Should be probably enabled in corresponding GPIO driver later, or made CLK_IS_CRITICAL. "gout_gpio_peri_clk" is actually used by LEDs on Exynos850-based dev board, so kernel hangs if this clock is not running. Other clocks were marked as "ignore unused" to prevent similar issues for other use cases or boards that might be added later. - "gout_cci_aclk": CLK_IS_CRITICAL CCI (Cache Coherent Interconnect): obviously is critical. - "gout_gic_clk": CLK_IS_CRITICAL GIC (Generic Interrupt Controller): obviously is critical. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Link: https://lore.kernel.org/r/20211121232741.6967-7-semen.protsenko@linaro.org
2021-11-22clk: samsung: exynos850: Implement CMU_CMGP domainSam Protsenko1-0/+100
CMU_CMGP clock domain provides clocks for CMGP IP-core (Common GPIO). CMGP module encapsulates next blocks: - 8 GPIO lines - 1 GPADC - 2 USI blocks, each can be configured to provide one of UART/SPI/HSI2C serial interfaces Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Link: https://lore.kernel.org/r/20211121232741.6967-5-semen.protsenko@linaro.org
2021-11-22clk: samsung: exynos850: Implement CMU_APM domainSam Protsenko1-1/+141
CMU_APM clock domain provides clocks for APM IP-core (Active Power Management). According to Exynos850 TRM, CMU_APM generates I3C, Mailbox, Speedy, Timer, WDT, RTC and PMU clocks for BLK_ALIVE. This patch adds next clocks: - bus clocks in CMU_TOP needed for CMU_APM - all internal CMU_APM clocks - leaf clocks for I3C, Speedy and RTC IP-cores - bus clocks for CMU_CMGP and CMU_CHUB CMU_APM doesn't belong to Power Domains, but platform driver is used for its registration to keep its bus clock always running. Otherwise rtc-s3c driver disables that clock and system freezes. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Link: https://lore.kernel.org/r/20211121232741.6967-3-semen.protsenko@linaro.org
2021-10-15clk: samsung: Introduce Exynos850 clock driverSam Protsenko1-0/+835
This is the initial implementation adding only basic clocks like UART, MMC, I2C and corresponding parent clocks. Design is influenced by Exynos5433 clock driver. Bus clock is enabled by default (in probe function) for all CMUs except CMU_TOP, the reasoning is as follows. By default if bus clock has no users its "enable count" value is 0. It might be actually running if it's already enabled in bootloader, but then in some cases it can be disabled by mistake. For example, such case was observed when dw_mci_probe() enabled the bus clock, then failed to do something and disabled that bus clock on error path. After that, even the attempt to read the 'clk_summary' file in DebugFS freezed forever, as CMU bus clock ended up being disabled and it wasn't possible to access CMU registers anymore. To avoid such cases, CMU driver must increment the ref count for that bus clock by running clk_prepare_enable(). There is already existing '.clk_name' field in struct samsung_cmu_info, exactly for that reason. It was added in commit 523d3de41f02 ("clk: samsung: exynos5433: Add support for runtime PM"), with next mentioning in commit message: > Also for each CMU there is one special parent clock, which has to be > enabled all the time when any access to CMU registers is being done. But that clock is actually only enabled in Exynos5433 clock driver right now. So the same code is added to exynos850_cmu_probe() function, As was described above, it might be helpful not only for PM reasons, but also to prevent possible erroneous clock gating on error paths. Another way to workaround that issue would be to use CLOCK_IS_CRITICAL flag for corresponding gate clocks. But that might be not very good design decision, as we might still want to disable that bus clock, e.g. on PM suspend. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Acked-by: Chanwoo Choi <cw00.choi@samsung.com> Link: https://lore.kernel.org/r/20211008154352.19519-6-semen.protsenko@linaro.org Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
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