diff mbox series

[V3,2/7] drm: bridge: samsung-dsim: Fix PMS Calculator on imx8m[mnp]

Message ID 20230502010759.17282-3-aford173@gmail.com
State New
Headers
Series drm: bridge: samsung-dsim: Support variable clocking |

Commit Message

Adam Ford May 2, 2023, 1:07 a.m. UTC 
  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>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 22 ++++++++++++++++++++--
 include/drm/bridge/samsung-dsim.h     |  3 +++
 2 files changed, 23 insertions(+), 2 deletions(-)

Comments

Frieder Schrempf May 3, 2023, 3:18 p.m. UTC | #1 
On 02.05.23 03:07, Adam Ford wrote:
> 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 on Kontron BL i.MX8MM with SN65DSI84 and ADV7535 bridges.

Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 2be3b58624c3..bf4b33d2de76 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 ba5484de2b30..a1a5b2b89a7a 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 {