[PATCH 6.4 321/800] drm: bridge: samsung-dsim: Fix PMS Calculator on imx8m[mnp]

Greg Kroah-Hartman
2023-07-16T20:07:52Z

From: Adam Ford <aford173@gmail.com>

[ Upstream commit 54f1a83c72250b182fa7722b0c5f6eb5e769598d ]

According to Table 13-45 of the i.MX8M Mini Reference Manual, the min
and max values for M and the frequency range for the VCO_out
calculator were incorrect. This information was contradicted in other
parts of the mini, nano and plus manuals. After reaching out to my
NXP Rep, when confronting him about discrepencies in the Nano manual,
he responded with:
"Yes it is definitely wrong, the one that is part
of the NOTE in MIPI_DPHY_M_PLLPMS register table against PMS_P,
PMS_M and PMS_S is not correct. I will report this to Doc team,
the one customer should be take into account is the Table 13-40
DPHY PLL Parameters and the Note above."

These updated values also match what is used in the NXP downstream
kernel.

To fix this, make new variables to hold the min and max values of m
and the minimum value of VCO_out, and update the PMS calculator to
use these new variables instead of using hard-coded values to keep
the backwards compatibility with other parts using this driver.

Fixes: 4d562c70c4dc ("drm: bridge: samsung-dsim: Add i.MX8M Mini/Nano support")
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # imx8mm-icore
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230526030559.326566-3-aford173@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/bridge/samsung-dsim.c | 22 ++++++++++++++++++++--
include/drm/bridge/samsung-dsim.h | 3 +++
2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index e0a402a85787c..3194cabb26b32 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -405,6 +405,9 @@ static const struct samsung_dsim_driver_data exynos3_dsi_driver_data = {
.num_bits_resol = 11,
.pll_p_offset = 13,
.reg_values = reg_values,
+ .m_min = 41,
+ .m_max = 125,
+ .min_freq = 500,
};

static const struct samsung_dsim_driver_data exynos4_dsi_driver_data = {
@@ -418,6 +421,9 @@ static const struct samsung_dsim_driver_data exynos4_dsi_driver_data = {
.num_bits_resol = 11,
.pll_p_offset = 13,
.reg_values = reg_values,
+ .m_min = 41,
+ .m_max = 125,
+ .min_freq = 500,
};

static const struct samsung_dsim_driver_data exynos5_dsi_driver_data = {
@@ -429,6 +435,9 @@ static const struct samsung_dsim_driver_data exynos5_dsi_driver_data = {
.num_bits_resol = 11,
.pll_p_offset = 13,
.reg_values = reg_values,
+ .m_min = 41,
+ .m_max = 125,
+ .min_freq = 500,
};

static const struct samsung_dsim_driver_data exynos5433_dsi_driver_data = {
@@ -441,6 +450,9 @@ static const struct samsung_dsim_driver_data exynos5433_dsi_driver_data = {
.num_bits_resol = 12,
.pll_p_offset = 13,
.reg_values = exynos5433_reg_values,
+ .m_min = 41,
+ .m_max = 125,
+ .min_freq = 500,
};

static const struct samsung_dsim_driver_data exynos5422_dsi_driver_data = {
@@ -453,6 +465,9 @@ static const struct samsung_dsim_driver_data exynos5422_dsi_driver_data = {
.num_bits_resol = 12,
.pll_p_offset = 13,
.reg_values = exynos5422_reg_values,
+ .m_min = 41,
+ .m_max = 125,
+ .min_freq = 500,
};

static const struct samsung_dsim_driver_data imx8mm_dsi_driver_data = {
@@ -469,6 +484,9 @@ static const struct samsung_dsim_driver_data imx8mm_dsi_driver_data = {
*/
.pll_p_offset = 14,
.reg_values = imx8mm_dsim_reg_values,
+ .m_min = 64,
+ .m_max = 1023,
+ .min_freq = 1050,
};

static const struct samsung_dsim_driver_data *
@@ -547,12 +565,12 @@ static unsigned long samsung_dsim_pll_find_pms(struct samsung_dsim *dsi,
tmp = (u64)fout * (_p << _s);
do_div(tmp, fin);
_m = tmp;
- if (_m < 41 || _m > 125)
+ if (_m < driver_data->m_min || _m > driver_data->m_max)
continue;

tmp = (u64)_m * fin;
do_div(tmp, _p);
- if (tmp < 500 * MHZ ||
+ if (tmp < driver_data->min_freq * MHZ ||
tmp > driver_data->max_freq * MHZ)
continue;

diff --git a/include/drm/bridge/samsung-dsim.h b/include/drm/bridge/samsung-dsim.h
index ba5484de2b30e..a1a5b2b89a7ab 100644
--- a/include/drm/bridge/samsung-dsim.h
+++ b/include/drm/bridge/samsung-dsim.h
@@ -54,11 +54,14 @@ struct samsung_dsim_driver_data {
unsigned int has_freqband:1;
unsigned int has_clklane_stop:1;
unsigned int num_clks;
+ unsigned int min_freq;
unsigned int max_freq;
unsigned int wait_for_reset;
unsigned int num_bits_resol;
unsigned int pll_p_offset;
const unsigned int *reg_values;
+ u16 m_min;
+ u16 m_max;
};

struct samsung_dsim_host_ops {
--
2.39.2