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[RESEND PATCH v7 2/2] drm/tidss: Move OLDI mode validation to OLDI bridge mode_valid hook

Swamil Jain posted 2 patches 3 months, 2 weeks ago
[RESEND PATCH v7 2/2] drm/tidss: Move OLDI mode validation to OLDI bridge mode_valid hook
Posted by Swamil Jain 3 months, 2 weeks ago 
From: Jayesh Choudhary <j-choudhary@ti.com>

After integrating OLDI support[0], it is necessary to identify which VP
instances use OLDI, since the OLDI driver owns the video port clock
(as a serial clock). Clock operations on these VPs must be delegated to
the OLDI driver, not handled by the TIDSS driver. This issue also
emerged in upstream discussions when DSI-related clock management was
attempted in the TIDSS driver[1].

To address this, add an 'is_ext_vp_clk' array to the 'tidss_device'
structure, marking a VP as 'true' during 'tidss_oldi_init()' and as
'false' during 'tidss_oldi_deinit()'. TIDSS then uses 'is_ext_vp_clk'
to skip clock validation checks in 'dispc_vp_mode_valid()' for VPs
under OLDI control.

Since OLDI uses the DSS VP clock directly as a serial interface and
manages its own rate, mode validation should be implemented in the OLDI
bridge's 'mode_valid' hook. This patch adds that logic, ensuring proper
delegation and avoiding spurious clock handling in the TIDSS driver.

[0]: https://lore.kernel.org/all/20250528122544.817829-1-aradhya.bhatia@linux.dev/
[1]: https://lore.kernel.org/all/DA6TT575Z82D.3MPK8HG5GRL8U@kernel.org/

Fixes: 7246e0929945 ("drm/tidss: Add OLDI bridge support")
Tested-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Swamil Jain <s-jain1@ti.com>
---
 drivers/gpu/drm/tidss/tidss_dispc.c |  2 ++
 drivers/gpu/drm/tidss/tidss_drv.h   |  2 ++
 drivers/gpu/drm/tidss/tidss_oldi.c  | 21 +++++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
index 07731b02490f..0c3337a7b163 100644
--- a/drivers/gpu/drm/tidss/tidss_dispc.c
+++ b/drivers/gpu/drm/tidss/tidss_dispc.c
@@ -1315,6 +1315,8 @@ static int check_pixel_clock(struct dispc_device *dispc,
 {
 	unsigned long round_clock;
 
+	if (dispc->tidss->is_ext_vp_clk[hw_videoport])
+		return 0;
 	round_clock = clk_round_rate(dispc->vp_clk[hw_videoport], clock);
 	/*
 	 * To keep the check consistent with dispc_vp_set_clk_rate(), we
diff --git a/drivers/gpu/drm/tidss/tidss_drv.h b/drivers/gpu/drm/tidss/tidss_drv.h
index 84454a4855d1..e1c1f41d8b4b 100644
--- a/drivers/gpu/drm/tidss/tidss_drv.h
+++ b/drivers/gpu/drm/tidss/tidss_drv.h
@@ -24,6 +24,8 @@ struct tidss_device {
 
 	const struct dispc_features *feat;
 	struct dispc_device *dispc;
+	bool is_ext_vp_clk[TIDSS_MAX_PORTS];
+
 
 	unsigned int num_crtcs;
 	struct drm_crtc *crtcs[TIDSS_MAX_PORTS];
diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/tidss/tidss_oldi.c
index 7688251beba2..d1a5fdac93ff 100644
--- a/drivers/gpu/drm/tidss/tidss_oldi.c
+++ b/drivers/gpu/drm/tidss/tidss_oldi.c
@@ -309,6 +309,24 @@ static u32 *tidss_oldi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
 	return input_fmts;
 }
 
+static enum drm_mode_status
+tidss_oldi_mode_valid(struct drm_bridge *bridge,
+		      const struct drm_display_info *info,
+		      const struct drm_display_mode *mode)
+{
+	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);
+	unsigned long round_clock;
+
+	round_clock = clk_round_rate(oldi->serial, mode->clock * 7 * 1000);
+	/*
+	 * To keep the check consistent with dispc_vp_set_clk_rate(),
+	 * we use the same 5% check here.
+	 */
+	if (dispc_pclk_diff(mode->clock * 7 * 1000, round_clock) > 5)
+		return -EINVAL;
+	return 0;
+}
+
 static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
 	.attach	= tidss_oldi_bridge_attach,
 	.atomic_pre_enable = tidss_oldi_atomic_pre_enable,
@@ -317,6 +335,7 @@ static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
 	.atomic_reset = drm_atomic_helper_bridge_reset,
+	.mode_valid = tidss_oldi_mode_valid,
 };
 
 static int get_oldi_mode(struct device_node *oldi_tx, int *companion_instance)
@@ -430,6 +449,7 @@ void tidss_oldi_deinit(struct tidss_device *tidss)
 	for (int i = 0; i < tidss->num_oldis; i++) {
 		if (tidss->oldis[i]) {
 			drm_bridge_remove(&tidss->oldis[i]->bridge);
+			tidss->is_ext_vp_clk[tidss->oldis[i]->parent_vp] = false;
 			tidss->oldis[i] = NULL;
 		}
 	}
@@ -580,6 +600,7 @@ int tidss_oldi_init(struct tidss_device *tidss)
 		oldi->bridge.timings = &default_tidss_oldi_timings;
 
 		tidss->oldis[tidss->num_oldis++] = oldi;
+		tidss->is_ext_vp_clk[oldi->parent_vp] = true;
 		oldi->tidss = tidss;
 
 		drm_bridge_add(&oldi->bridge);
Re: [RESEND PATCH v7 2/2] drm/tidss: Move OLDI mode validation to OLDI bridge mode_valid hook
Posted by Tomi Valkeinen 3 months, 1 week ago 
Hi,

On 28/10/2025 05:39, Swamil Jain wrote:
> From: Jayesh Choudhary <j-choudhary@ti.com>
> 
> After integrating OLDI support[0], it is necessary to identify which VP
> instances use OLDI, since the OLDI driver owns the video port clock
> (as a serial clock). Clock operations on these VPs must be delegated to
> the OLDI driver, not handled by the TIDSS driver. This issue also
> emerged in upstream discussions when DSI-related clock management was
> attempted in the TIDSS driver[1].
> 
> To address this, add an 'is_ext_vp_clk' array to the 'tidss_device'
> structure, marking a VP as 'true' during 'tidss_oldi_init()' and as
> 'false' during 'tidss_oldi_deinit()'. TIDSS then uses 'is_ext_vp_clk'
> to skip clock validation checks in 'dispc_vp_mode_valid()' for VPs
> under OLDI control.
> 
> Since OLDI uses the DSS VP clock directly as a serial interface and
> manages its own rate, mode validation should be implemented in the OLDI
> bridge's 'mode_valid' hook. This patch adds that logic, ensuring proper
> delegation and avoiding spurious clock handling in the TIDSS driver.
> 
> [0]: https://lore.kernel.org/all/20250528122544.817829-1-aradhya.bhatia@linux.dev/
> [1]: https://lore.kernel.org/all/DA6TT575Z82D.3MPK8HG5GRL8U@kernel.org/
> 
> Fixes: 7246e0929945 ("drm/tidss: Add OLDI bridge support")
> Tested-by: Michael Walle <mwalle@kernel.org>
> Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
> Signed-off-by: Swamil Jain <s-jain1@ti.com>
> ---
>  drivers/gpu/drm/tidss/tidss_dispc.c |  2 ++
>  drivers/gpu/drm/tidss/tidss_drv.h   |  2 ++
>  drivers/gpu/drm/tidss/tidss_oldi.c  | 21 +++++++++++++++++++++
>  3 files changed, 25 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
> index 07731b02490f..0c3337a7b163 100644
> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c
> @@ -1315,6 +1315,8 @@ static int check_pixel_clock(struct dispc_device *dispc,
>  {
>  	unsigned long round_clock;
>  
> +	if (dispc->tidss->is_ext_vp_clk[hw_videoport])
> +		return 0;

Add empty line here. Also, add a short comment what this check is about.

>  	round_clock = clk_round_rate(dispc->vp_clk[hw_videoport], clock);
>  	/*
>  	 * To keep the check consistent with dispc_vp_set_clk_rate(), we
> diff --git a/drivers/gpu/drm/tidss/tidss_drv.h b/drivers/gpu/drm/tidss/tidss_drv.h
> index 84454a4855d1..e1c1f41d8b4b 100644
> --- a/drivers/gpu/drm/tidss/tidss_drv.h
> +++ b/drivers/gpu/drm/tidss/tidss_drv.h
> @@ -24,6 +24,8 @@ struct tidss_device {
>  
>  	const struct dispc_features *feat;
>  	struct dispc_device *dispc;
> +	bool is_ext_vp_clk[TIDSS_MAX_PORTS];
> +
>  
>  	unsigned int num_crtcs;
>  	struct drm_crtc *crtcs[TIDSS_MAX_PORTS];
> diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/tidss/tidss_oldi.c
> index 7688251beba2..d1a5fdac93ff 100644
> --- a/drivers/gpu/drm/tidss/tidss_oldi.c
> +++ b/drivers/gpu/drm/tidss/tidss_oldi.c
> @@ -309,6 +309,24 @@ static u32 *tidss_oldi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
>  	return input_fmts;
>  }
>  
> +static enum drm_mode_status
> +tidss_oldi_mode_valid(struct drm_bridge *bridge,
> +		      const struct drm_display_info *info,
> +		      const struct drm_display_mode *mode)
> +{
> +	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);
> +	unsigned long round_clock;
> +
> +	round_clock = clk_round_rate(oldi->serial, mode->clock * 7 * 1000);
> +	/*
> +	 * To keep the check consistent with dispc_vp_set_clk_rate(),
> +	 * we use the same 5% check here.
> +	 */
> +	if (dispc_pclk_diff(mode->clock * 7 * 1000, round_clock) > 5)
> +		return -EINVAL;

Add an empty line here.

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

> +	return 0;
> +}
> +
>  static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
>  	.attach	= tidss_oldi_bridge_attach,
>  	.atomic_pre_enable = tidss_oldi_atomic_pre_enable,
> @@ -317,6 +335,7 @@ static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
>  	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
>  	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
>  	.atomic_reset = drm_atomic_helper_bridge_reset,
> +	.mode_valid = tidss_oldi_mode_valid,
>  };
>  
>  static int get_oldi_mode(struct device_node *oldi_tx, int *companion_instance)
> @@ -430,6 +449,7 @@ void tidss_oldi_deinit(struct tidss_device *tidss)
>  	for (int i = 0; i < tidss->num_oldis; i++) {
>  		if (tidss->oldis[i]) {
>  			drm_bridge_remove(&tidss->oldis[i]->bridge);
> +			tidss->is_ext_vp_clk[tidss->oldis[i]->parent_vp] = false;
>  			tidss->oldis[i] = NULL;
>  		}
>  	}
> @@ -580,6 +600,7 @@ int tidss_oldi_init(struct tidss_device *tidss)
>  		oldi->bridge.timings = &default_tidss_oldi_timings;
>  
>  		tidss->oldis[tidss->num_oldis++] = oldi;
> +		tidss->is_ext_vp_clk[oldi->parent_vp] = true;
>  		oldi->tidss = tidss;
>  
>  		drm_bridge_add(&oldi->bridge);
Re: [RESEND PATCH v7 2/2] drm/tidss: Move OLDI mode validation to OLDI bridge mode_valid hook
Posted by Swamil Jain 3 months, 1 week ago 
Hi Tomi,

On 03-11-2025 13:35, Tomi Valkeinen wrote:
> Hi,
> 
> On 28/10/2025 05:39, Swamil Jain wrote:
>> From: Jayesh Choudhary <j-choudhary@ti.com>
>>
>> After integrating OLDI support[0], it is necessary to identify which VP
>> instances use OLDI, since the OLDI driver owns the video port clock
>> (as a serial clock). Clock operations on these VPs must be delegated to
>> the OLDI driver, not handled by the TIDSS driver. This issue also
>> emerged in upstream discussions when DSI-related clock management was
>> attempted in the TIDSS driver[1].
>>
>> To address this, add an 'is_ext_vp_clk' array to the 'tidss_device'
>> structure, marking a VP as 'true' during 'tidss_oldi_init()' and as
>> 'false' during 'tidss_oldi_deinit()'. TIDSS then uses 'is_ext_vp_clk'
>> to skip clock validation checks in 'dispc_vp_mode_valid()' for VPs
>> under OLDI control.
>>
>> Since OLDI uses the DSS VP clock directly as a serial interface and
>> manages its own rate, mode validation should be implemented in the OLDI
>> bridge's 'mode_valid' hook. This patch adds that logic, ensuring proper
>> delegation and avoiding spurious clock handling in the TIDSS driver.
>>
>> [0]: https://lore.kernel.org/all/20250528122544.817829-1-aradhya.bhatia@linux.dev/
>> [1]: https://lore.kernel.org/all/DA6TT575Z82D.3MPK8HG5GRL8U@kernel.org/
>>
>> Fixes: 7246e0929945 ("drm/tidss: Add OLDI bridge support")
>> Tested-by: Michael Walle <mwalle@kernel.org>
>> Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
>> Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
>> Signed-off-by: Swamil Jain <s-jain1@ti.com>
>> ---
>>   drivers/gpu/drm/tidss/tidss_dispc.c |  2 ++
>>   drivers/gpu/drm/tidss/tidss_drv.h   |  2 ++
>>   drivers/gpu/drm/tidss/tidss_oldi.c  | 21 +++++++++++++++++++++
>>   3 files changed, 25 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
>> index 07731b02490f..0c3337a7b163 100644
>> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
>> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c
>> @@ -1315,6 +1315,8 @@ static int check_pixel_clock(struct dispc_device *dispc,
>>   {
>>   	unsigned long round_clock;
>>   
>> +	if (dispc->tidss->is_ext_vp_clk[hw_videoport])
>> +		return 0;
> 
> Add empty line here. Also, add a short comment what this check is about.
> 
>>   	round_clock = clk_round_rate(dispc->vp_clk[hw_videoport], clock);
>>   	/*
>>   	 * To keep the check consistent with dispc_vp_set_clk_rate(), we
>> diff --git a/drivers/gpu/drm/tidss/tidss_drv.h b/drivers/gpu/drm/tidss/tidss_drv.h
>> index 84454a4855d1..e1c1f41d8b4b 100644
>> --- a/drivers/gpu/drm/tidss/tidss_drv.h
>> +++ b/drivers/gpu/drm/tidss/tidss_drv.h
>> @@ -24,6 +24,8 @@ struct tidss_device {
>>   
>>   	const struct dispc_features *feat;
>>   	struct dispc_device *dispc;
>> +	bool is_ext_vp_clk[TIDSS_MAX_PORTS];
>> +
>>   
>>   	unsigned int num_crtcs;
>>   	struct drm_crtc *crtcs[TIDSS_MAX_PORTS];
>> diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/tidss/tidss_oldi.c
>> index 7688251beba2..d1a5fdac93ff 100644
>> --- a/drivers/gpu/drm/tidss/tidss_oldi.c
>> +++ b/drivers/gpu/drm/tidss/tidss_oldi.c
>> @@ -309,6 +309,24 @@ static u32 *tidss_oldi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
>>   	return input_fmts;
>>   }
>>   
>> +static enum drm_mode_status
>> +tidss_oldi_mode_valid(struct drm_bridge *bridge,
>> +		      const struct drm_display_info *info,
>> +		      const struct drm_display_mode *mode)
>> +{
>> +	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);
>> +	unsigned long round_clock;
>> +
>> +	round_clock = clk_round_rate(oldi->serial, mode->clock * 7 * 1000);
>> +	/*
>> +	 * To keep the check consistent with dispc_vp_set_clk_rate(),
>> +	 * we use the same 5% check here.
>> +	 */
>> +	if (dispc_pclk_diff(mode->clock * 7 * 1000, round_clock) > 5)
>> +		return -EINVAL;
> 
> Add an empty line here.
Sure, will add and respin. Thanks for reviewing.

Regards,
Swamil>
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> 
>> +	return 0;
>> +}
>> +
>>   static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
>>   	.attach	= tidss_oldi_bridge_attach,
>>   	.atomic_pre_enable = tidss_oldi_atomic_pre_enable,
>> @@ -317,6 +335,7 @@ static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
>>   	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
>>   	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
>>   	.atomic_reset = drm_atomic_helper_bridge_reset,
>> +	.mode_valid = tidss_oldi_mode_valid,
>>   };
>>   
>>   static int get_oldi_mode(struct device_node *oldi_tx, int *companion_instance)
>> @@ -430,6 +449,7 @@ void tidss_oldi_deinit(struct tidss_device *tidss)
>>   	for (int i = 0; i < tidss->num_oldis; i++) {
>>   		if (tidss->oldis[i]) {
>>   			drm_bridge_remove(&tidss->oldis[i]->bridge);
>> +			tidss->is_ext_vp_clk[tidss->oldis[i]->parent_vp] = false;
>>   			tidss->oldis[i] = NULL;
>>   		}
>>   	}
>> @@ -580,6 +600,7 @@ int tidss_oldi_init(struct tidss_device *tidss)
>>   		oldi->bridge.timings = &default_tidss_oldi_timings;
>>   
>>   		tidss->oldis[tidss->num_oldis++] = oldi;
>> +		tidss->is_ext_vp_clk[oldi->parent_vp] = true;
>>   		oldi->tidss = tidss;
>>   
>>   		drm_bridge_add(&oldi->bridge);
>

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