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drm: lcdif: change burst size to 256B

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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: 9db35bb349 ("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
This commit is contained in:
Marco Felsch
2022-11-01 17:46:15 +01:00
committed by Marek Vasut
parent da7ffb9660
commit 2215cb3be5
2 changed files with 16 additions and 2 deletions
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drivers/gpu/drm/mxsfb/lcdif_kms.c
+12 -2
View File
@@ -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)
drivers/gpu/drm/mxsfb/lcdif_regs.h
+4
View File
@@ -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)