diff options
| author | Marco Felsch <m.felsch@pengutronix.de> | 2022-11-01 19:46:15 +0300 |
|---|---|---|
| committer | Marek Vasut <marex@denx.de> | 2022-11-01 20:34:07 +0300 |
| commit | 2215cb3be5c28a1fd43036550c00c2371aeeba95 (patch) | |
| tree | d10d51926c1432ae3b8a6b0ee12be0efeaee848c /drivers/gpu/drm/mxsfb | |
| parent | da7ffb9660c96eec4167f177eb1cb6e78dd7fc0e (diff) | |
| download | linux-2215cb3be5c28a1fd43036550c00c2371aeeba95.tar.xz | |
drm: lcdif: change burst size to 256B
If a axi bus master with a higher priority do a lot of memory access
FIFO underruns can be inspected. Increase the burst size to 256B to
avoid such underruns and to improve the memory access efficiency.
Fixes: 9db35bb349a0 ("drm: lcdif: Add support for i.MX8MP LCDIF variant")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221101164615.778299-1-m.felsch@pengutronix.de
Diffstat (limited to 'drivers/gpu/drm/mxsfb')
| -rw-r--r-- | drivers/gpu/drm/mxsfb/lcdif_kms.c | 14 | ||||
| -rw-r--r-- | drivers/gpu/drm/mxsfb/lcdif_regs.h | 4 |
2 files changed, 16 insertions, 2 deletions
diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c index 33ee40876994..f0ad6e2a9352 100644 --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c @@ -314,8 +314,18 @@ static void lcdif_set_mode(struct lcdif_drm_private *lcdif, u32 bus_flags) CTRLDESCL0_1_WIDTH(m->hdisplay), lcdif->base + LCDC_V8_CTRLDESCL0_1); - writel(CTRLDESCL0_3_PITCH(lcdif->crtc.primary->state->fb->pitches[0]), - lcdif->base + LCDC_V8_CTRLDESCL0_3); + /* + * Undocumented P_SIZE and T_SIZE register but those written in the + * downstream kernel those registers control the AXI burst size. As of + * now there are two known values: + * 1 - 128Byte + * 2 - 256Byte + * Downstream set it to 256B burst size to improve the memory + * efficiency so set it here too. + */ + ctrl = CTRLDESCL0_3_P_SIZE(2) | CTRLDESCL0_3_T_SIZE(2) | + CTRLDESCL0_3_PITCH(lcdif->crtc.primary->state->fb->pitches[0]); + writel(ctrl, lcdif->base + LCDC_V8_CTRLDESCL0_3); } static void lcdif_enable_controller(struct lcdif_drm_private *lcdif) diff --git a/drivers/gpu/drm/mxsfb/lcdif_regs.h b/drivers/gpu/drm/mxsfb/lcdif_regs.h index 2d3920b8371e..fb74eb5ccbf1 100644 --- a/drivers/gpu/drm/mxsfb/lcdif_regs.h +++ b/drivers/gpu/drm/mxsfb/lcdif_regs.h @@ -190,6 +190,10 @@ #define CTRLDESCL0_1_WIDTH(n) ((n) & 0xffff) #define CTRLDESCL0_1_WIDTH_MASK GENMASK(15, 0) +#define CTRLDESCL0_3_P_SIZE(n) (((n) << 20) & CTRLDESCL0_3_P_SIZE_MASK) +#define CTRLDESCL0_3_P_SIZE_MASK GENMASK(22, 20) +#define CTRLDESCL0_3_T_SIZE(n) (((n) << 16) & CTRLDESCL0_3_T_SIZE_MASK) +#define CTRLDESCL0_3_T_SIZE_MASK GENMASK(17, 16) #define CTRLDESCL0_3_PITCH(n) ((n) & 0xffff) #define CTRLDESCL0_3_PITCH_MASK GENMASK(15, 0) |