Re: [PATCH v3 drm-dp 06/11] drm/hisilicon/hibmc: add dp mode valid check

[Yongbang Shi <shiyongbang@huawei.com>]

> On Fri, Jul 18, 2025 at 02:51:20PM +0800, Yongbang Shi wrote:
>> From: Baihan Li <libaihan@huawei.com>
>>
>> If DP is connected, add mode check and BW check in mode_valid_ctx() to
>> ensure DP's cfg is usable.
>>
>> For example: Some DP's mode(1920x1080 60HZ 138.5 MHz) gives to drm,
>> however, the GPU is configured for 148MHz in display_ctrl_adjust() by
>> looking up the table of struct hibmc_pll_table{}. This difference will
>> cause the DP to not display because the clock the DP gets via drm frame
>> is 138MHz.
>>
>> Fixes: f9698f802e50 ("drm/hisilicon/hibmc: Restructuring the header dp_reg.h")
>> Signed-off-by: Baihan Li <libaihan@huawei.com>
>> Signed-off-by: Yongbang Shi <shiyongbang@huawei.com>
>> ---
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c    | 10 ++++
>>   drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h    |  6 +++
>>   .../gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c    | 51 +++++++++++++++++++
>>   3 files changed, 67 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> index b4d612047f36..7fbd51ffd778 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.c
>> @@ -276,6 +276,16 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp)
>>   	dp->dp_dev->link.status.channel_equalized = false;
>>   }
>>   
>> +u8 hibmc_dp_get_link_rate(struct hibmc_dp *dp)
>> +{
>> +	return dp->dp_dev->link.cap.link_rate;
>> +}
>> +
>> +u8 hibmc_dp_get_lanes(struct hibmc_dp *dp)
>> +{
>> +	return dp->dp_dev->link.cap.lanes;
>> +}
>> +
>>   static const struct hibmc_dp_color_raw g_rgb_raw[] = {
>>   	{CBAR_COLOR_BAR, 0x000, 0x000, 0x000},
>>   	{CBAR_WHITE,     0xfff, 0xfff, 0xfff},
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
>> index 9b45e88e47e4..0059a2648a38 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_hw.h
>> @@ -12,6 +12,10 @@
>>   #include <drm/drm_print.h>
>>   #include <drm/display/drm_dp_helper.h>
>>   
>> +/* 27 * 10000000 * 80% = 216000000 */
>> +#define DP_MODE_VALI_CAL	216000000
>> +#define BPP_24				24
>> +
>>   struct hibmc_dp_dev;
>>   
>>   enum hibmc_dp_cbar_pattern {
>> @@ -62,5 +66,7 @@ void hibmc_dp_reset_link(struct hibmc_dp *dp);
>>   void hibmc_dp_hpd_cfg(struct hibmc_dp *dp);
>>   void hibmc_dp_enable_int(struct hibmc_dp *dp);
>>   void hibmc_dp_disable_int(struct hibmc_dp *dp);
>> +u8 hibmc_dp_get_link_rate(struct hibmc_dp *dp);
>> +u8 hibmc_dp_get_lanes(struct hibmc_dp *dp);
>>   
>>   #endif
>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> index 354e18bb2998..99b30a6c7e06 100644
>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_dp.c
>> @@ -15,6 +15,28 @@
>>   
>>   #define DP_MASKED_SINK_HPD_PLUG_INT	BIT(2)
>>   
>> +struct hibmc_dp_disp_clk {
>> +	u16 hdisplay;
>> +	u16 vdisplay;
>> +	u32 clock;
>> +};
>> +
>> +static const struct hibmc_dp_disp_clk hibmc_dp_clk_table[] = {
>> +	{640, 480, 25175}, /* 25175 khz */
>> +	{800, 600, 40000}, /* 40000 khz */
>> +	{1024, 768, 65000}, /* 65000 khz */
>> +	{1152, 864, 80000}, /* 80000 khz */
>> +	{1280, 768, 79500}, /* 79500 khz */
>> +	{1280, 720, 74250}, /* 74250 khz */
>> +	{1280, 960, 108000}, /* 108000 khz */
>> +	{1280, 1024, 108000}, /* 108000 khz */
>> +	{1440, 900, 106500}, /* 106500 khz */
>> +	{1600, 900, 108000}, /* 108000 khz */
>> +	{1600, 1200, 162000}, /* 162000 khz */
>> +	{1920, 1080, 148500}, /* 148500 khz */
>> +	{1920, 1200, 193250}, /* 193250 khz */
>> +};
> I generally think that these kind of tables are too limiting. Please try
> to achieve the same by checking the clock with the PLL code instead of
> checking the modes against the table.

Okay!


>> +
>>   static int hibmc_dp_connector_get_modes(struct drm_connector *connector)
>>   {
>>   	const struct drm_edid *drm_edid;
>> @@ -42,9 +64,38 @@ static int hibmc_dp_detect(struct drm_connector *connector,
>>   	return connector_status_disconnected;
>>   }
>>   
>> +static int hibmc_dp_mode_valid(struct drm_connector *connector,
>> +			       const struct drm_display_mode *mode,
>> +			       struct drm_modeset_acquire_ctx *ctx,
>> +			       enum drm_mode_status *status)
>> +{
>> +	struct hibmc_dp *dp = to_hibmc_dp(connector);
>> +	u64 cur_val, max_val;
>> +
>> +	/* check DP link BW */
>> +	cur_val = (u64)mode->htotal * mode->vtotal * drm_mode_vrefresh(mode) * BPP_24;
>> +	max_val = (u64)hibmc_dp_get_link_rate(dp) * DP_MODE_VALI_CAL * hibmc_dp_get_lanes(dp);
>> +
>> +	*status = cur_val > max_val ? MODE_CLOCK_HIGH : MODE_OK;
>> +
>> +	/* check the clock */
>> +	for (size_t i = 0; i < ARRAY_SIZE(hibmc_dp_clk_table); i++) {
>> +		if (hibmc_dp_clk_table[i].hdisplay == mode->hdisplay &&
>> +		    hibmc_dp_clk_table[i].vdisplay == mode->vdisplay) {
>> +			if (hibmc_dp_clk_table[i].clock != mode->clock) {
>> +				*status = MODE_CLOCK_RANGE;
>> +				return 0;
>> +			}
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   static const struct drm_connector_helper_funcs hibmc_dp_conn_helper_funcs = {
>>   	.get_modes = hibmc_dp_connector_get_modes,
>>   	.detect_ctx = hibmc_dp_detect,
>> +	.mode_valid_ctx = hibmc_dp_mode_valid,
>>   };
>>   
>>   static int hibmc_dp_late_register(struct drm_connector *connector)
>> -- 
>> 2.33.0
>>