From c6930d93e282389c191b46683bf0c020e425f63d Mon Sep 17 00:00:00 2001
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: Wed, 9 Aug 2023 16:56:41 +0200
Subject: drm: bridge: samsung-dsim: Fix waiting for empty cmd transfer FIFO on
older Exynos
Git-commit: 15f389da11257b806da75a070cfa41ca0cc15aae
Patch-mainline: v6.7-rc1
References: jsc#PED-3527 jsc#PED-5475 jsc#PED-6068 jsc#PED-6070 jsc#PED-6116 jsc#PED-6120 jsc#PED-5065 jsc#PED-5477 jsc#PED-5511 jsc#PED-6041 jsc#PED-6069 jsc#PED-6071
Samsung DSIM used in older Exynos SoCs (like Exynos 4210, 4x12, 3250)
doesn't report empty level of packer header FIFO. In case of those SoCs,
use the old way of waiting for empty command tranfsfer FIFO, removed
recently by commit 14806c641582 ("drm: bridge: samsung-dsim: Drain command transfer FIFO before transfer").
Fixes: 14806c641582 ("drm: bridge: samsung-dsim: Drain command transfer FIFO before transfer")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230809145641.3213210-1-m.szyprowski@samsung.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/bridge/samsung-dsim.c | 18 ++++++++++++++++--
include/drm/bridge/samsung-dsim.h | 1 +
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 6f2ca74238d1..19bdb32dbc9a 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -413,6 +413,7 @@ static const struct samsung_dsim_driver_data exynos3_dsi_driver_data = {
.m_min = 41,
.m_max = 125,
.min_freq = 500,
+ .has_broken_fifoctrl_emptyhdr = 1,
};
static const struct samsung_dsim_driver_data exynos4_dsi_driver_data = {
@@ -429,6 +430,7 @@ static const struct samsung_dsim_driver_data exynos4_dsi_driver_data = {
.m_min = 41,
.m_max = 125,
.min_freq = 500,
+ .has_broken_fifoctrl_emptyhdr = 1,
};
static const struct samsung_dsim_driver_data exynos5_dsi_driver_data = {
@@ -1010,8 +1012,20 @@ static int samsung_dsim_wait_for_hdr_fifo(struct samsung_dsim *dsi)
do {
u32 reg = samsung_dsim_read(dsi, DSIM_FIFOCTRL_REG);
- if (reg & DSIM_SFR_HEADER_EMPTY)
- return 0;
+ if (!dsi->driver_data->has_broken_fifoctrl_emptyhdr) {
+ if (reg & DSIM_SFR_HEADER_EMPTY)
+ return 0;
+ } else {
+ if (!(reg & DSIM_SFR_HEADER_FULL)) {
+ /*
+ * Wait a little bit, so the pending data can
+ * actually leave the FIFO to avoid overflow.
+ */
+ if (!cond_resched())
+ usleep_range(950, 1050);
+ return 0;
+ }
+ }
if (!cond_resched())
usleep_range(950, 1050);
diff --git a/include/drm/bridge/samsung-dsim.h b/include/drm/bridge/samsung-dsim.h
index 05100e91ecb9..6fc9bb2979e4 100644
--- a/include/drm/bridge/samsung-dsim.h
+++ b/include/drm/bridge/samsung-dsim.h
@@ -53,6 +53,7 @@ struct samsung_dsim_driver_data {
unsigned int plltmr_reg;
unsigned int has_freqband:1;
unsigned int has_clklane_stop:1;
+ unsigned int has_broken_fifoctrl_emptyhdr:1;
unsigned int num_clks;
unsigned int min_freq;
unsigned int max_freq;
--
2.43.0