diff options
author | Linus Walleij <linus.walleij@linaro.org> | 2023-06-16 23:42:23 +0300 |
---|---|---|
committer | Ulf Hansson <ulf.hansson@linaro.org> | 2023-06-19 14:14:26 +0300 |
commit | 7be5ac5f7a4890422920d6d91f94fff5d114d076 (patch) | |
tree | 01b7d50cdae1c49055b716aaeb36c36664601db2 | |
parent | e1a2485cc367cd0efe6821e2d8deef863c4ba250 (diff) | |
download | linux-7be5ac5f7a4890422920d6d91f94fff5d114d076.tar.xz |
mmc: mmci: Make busy complete state machine explicit
This refactors the ->busy_complete() callback currently
only used by Ux500 and STM32 to handle busy detection on
hardware where one and the same IRQ is fired whether we get
a start or an end signal on busy detect.
The code is currently using the cached status from the
command IRQ in ->busy_status as a state to select what to
do next: if this state is non-zero we are waiting for
IRQs and if it is zero we treat the state as the starting
point for a busy detect wait cycle.
Make this explicit by creating a state machine where the
->busy_complete callback moves between three states.
The Ux500 busy detect code currently assumes this order:
we enable the busy detect IRQ, get a busy start IRQ, then a
busy end IRQ, and then we clear and mask this IRQ and
proceed.
We insert debug prints for unexpected states.
This works as before on most cards, however on a
problematic card that is not working with busy detect, and
which I have been debugging, the following happens a lot:
[ 3.380554] mmci-pl18x 80005000.mmc: no busy signalling in time
[ 3.387420] mmci-pl18x 80005000.mmc: no busy signalling in time
[ 3.394561] mmci-pl18x 80005000.mmc: lost busy status
when waiting for busy start IRQ
This probably means that the busy detect start IRQ has
already occurred when we start executing the
->busy_complete() callbacks, and the busy detect end IRQ
is counted as the start IRQ, and this is what is causing
the card to not be detected properly.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v7-5-69a7164f2a61@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
-rw-r--r-- | drivers/mmc/host/mmci.c | 49 | ||||
-rw-r--r-- | drivers/mmc/host/mmci.h | 14 |
2 files changed, 45 insertions, 18 deletions
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index 9f92f39fec14..4ab0c622dff3 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -680,6 +680,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) writel(host->variant->busy_detect_mask, base + MMCICLEAR); writel(readl(base + MMCIMASK0) & ~host->variant->busy_detect_mask, base + MMCIMASK0); + host->busy_state = MMCI_BUSY_DONE; host->busy_status = 0; return true; } @@ -697,7 +698,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) * while, to allow it to be set, but tests indicates that it * isn't needed. */ - if (!host->busy_status) { + if (host->busy_state == MMCI_BUSY_DONE) { status = readl(base + MMCISTATUS); if (status & host->variant->busy_detect_flag) { writel(readl(base + MMCIMASK0) | @@ -705,6 +706,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) base + MMCIMASK0); host->busy_status = status & (MCI_CMDSENT | MCI_CMDRESPEND); + host->busy_state = MMCI_BUSY_WAITING_FOR_START_IRQ; return false; } } @@ -720,25 +722,34 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) * both the start and the end interrupts needs to be cleared, * one after the other. So, clear the busy start IRQ here. */ - if (host->busy_status && - (status & host->variant->busy_detect_flag)) { - host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); - writel(host->variant->busy_detect_mask, base + MMCICLEAR); - return false; + if (host->busy_state == MMCI_BUSY_WAITING_FOR_START_IRQ) { + if (status & host->variant->busy_detect_flag) { + host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); + writel(host->variant->busy_detect_mask, base + MMCICLEAR); + host->busy_state = MMCI_BUSY_WAITING_FOR_END_IRQ; + return false; + } else { + dev_dbg(mmc_dev(host->mmc), + "lost busy status when waiting for busy start IRQ\n"); + writel(host->variant->busy_detect_mask, base + MMCICLEAR); + writel(readl(base + MMCIMASK0) & + ~host->variant->busy_detect_mask, base + MMCIMASK0); + host->busy_state = MMCI_BUSY_DONE; + host->busy_status = 0; + return true; + } } - /* - * If there is a command in-progress that has been successfully - * sent and the busy bit isn't set, it means we have received - * the busy end IRQ. Clear and mask the IRQ, then continue to - * process the command. - */ - if (host->busy_status) { - writel(host->variant->busy_detect_mask, base + MMCICLEAR); - - writel(readl(base + MMCIMASK0) & - ~host->variant->busy_detect_mask, base + MMCIMASK0); - host->busy_status = 0; + if (host->busy_state == MMCI_BUSY_WAITING_FOR_END_IRQ) { + if (!(status & host->variant->busy_detect_flag)) { + host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); + host->busy_state = MMCI_BUSY_DONE; + return true; + } else { + dev_dbg(mmc_dev(host->mmc), + "busy status still asserted when handling busy end IRQ - will keep waiting\n"); + return false; + } } return true; @@ -1268,6 +1279,8 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c) } host->busy_status = 0; + host->busy_state = MMCI_BUSY_DONE; + if (host->variant->busy_timeout && cmd->flags & MMC_RSP_BUSY) { if (!cmd->busy_timeout) cmd->busy_timeout = 10 * MSEC_PER_SEC; diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h index e1a9b96a3396..12a7bbd3ce26 100644 --- a/drivers/mmc/host/mmci.h +++ b/drivers/mmc/host/mmci.h @@ -262,6 +262,19 @@ struct dma_chan; struct mmci_host; /** + * enum mmci_busy_state - enumerate the busy detect wait states + * + * This is used for the state machine waiting for different busy detect + * interrupts on hardware that fire a single IRQ for start and end of + * the busy detect phase on DAT0. + */ +enum mmci_busy_state { + MMCI_BUSY_WAITING_FOR_START_IRQ, + MMCI_BUSY_WAITING_FOR_END_IRQ, + MMCI_BUSY_DONE, +}; + +/** * struct variant_data - MMCI variant-specific quirks * @clkreg: default value for MCICLOCK register * @clkreg_enable: enable value for MMCICLOCK register @@ -409,6 +422,7 @@ struct mmci_host { u32 clk_reg; u32 clk_reg_add; u32 datactrl_reg; + enum mmci_busy_state busy_state; u32 busy_status; u32 mask1_reg; u8 vqmmc_enabled:1; |