[PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[Jérémie Dautheribes]

Hello everyone,

This patch series add support for the Crystal Clear Technology
CMT430B19N00 4.3" 480x272 TFT-LCD panel.
It also adds Crystal Clear Technology to vendor-prefixes.yaml.

Please note that unfortunately there is no public datasheet available
for this panel.

Changes in v2:
  - add link to the Crystal Clear Technology website in commit message, as
  suggested by Conor Dooley and Neil Armstrong.


Regards,

Jérémie

Jérémie Dautheribes (3):
  dt-bindings: Add Crystal Clear Technology vendor prefix
  dt-bindings: display: simple: add support for Crystal Clear
    CMT430B19N00
  drm/panel: simple: add CMT430B19N00 LCD panel support

 .../bindings/display/panel/panel-simple.yaml  |  2 ++
 .../devicetree/bindings/vendor-prefixes.yaml  |  2 ++
 drivers/gpu/drm/panel/panel-simple.c          | 29 +++++++++++++++++++
 3 files changed, 33 insertions(+)

-- 
2.34.1
---
- Link to v1: https://lore.kernel.org/all/20240223134517.728568-1-jeremie.dautheribes@bootlin.com/

[PATCH v2 1/3] dt-bindings: Add Crystal Clear Technology vendor prefix

[Jérémie Dautheribes]

Update Documentation/devicetree/bindings/vendor-prefixes.yaml to
include "cct" as a vendor prefix for "Crystal Clear Technology". CCT is
the vendor of the CMT430B19N00 TFT-LCD panel.

Link: http://www.cct.com.my/
Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
---
 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index fef2e12b504e..96e47742e250 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -248,6 +248,8 @@ patternProperties:
     description: Catalyst Semiconductor, Inc.
   "^cavium,.*":
     description: Cavium, Inc.
+  "^cct,.*":
+    description: Crystal Clear Technology Sdn. Bhd.
   "^cdns,.*":
     description: Cadence Design Systems Inc.
   "^cdtech,.*":
-- 
2.34.1

[PATCH v2 2/3] dt-bindings: display: simple: add support for Crystal Clear CMT430B19N00

[Jérémie Dautheribes]

Add Crystal Clear Technology CMT430B19N00 4.3" 480x272 TFT-LCD panel
compatible string.

Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
---
 .../devicetree/bindings/display/panel/panel-simple.yaml         | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/panel-simple.yaml b/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
index a95445f40870..c575f7c4b745 100644
--- a/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
+++ b/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
@@ -91,6 +91,8 @@ properties:
       - boe,nv133fhm-n62
         # BOE NV140FHM-N49 14.0" FHD a-Si FT panel
       - boe,nv140fhmn49
+        # Crystal Clear Technology CMT430B19N00 4.3" 480x272 TFT-LCD panel
+      - cct,cmt430b19n00
         # CDTech(H.K.) Electronics Limited 4.3" 480x272 color TFT-LCD panel
       - cdtech,s043wq26h-ct7
         # CDTech(H.K.) Electronics Limited 7" WSVGA (1024x600) TFT LCD Panel
-- 
2.34.1

[PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support

[Jérémie Dautheribes]

Add support for Crystal Clear Technology CMT430B19N00 4.3" 480x272
TFT-LCD panel.

Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
---
 drivers/gpu/drm/panel/panel-simple.c | 29 ++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 20e3df1c59d4..b940220f56e2 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -1457,6 +1457,32 @@ static const struct panel_desc boe_hv070wsa = {
 	.connector_type = DRM_MODE_CONNECTOR_LVDS,
 };
 
+static const struct drm_display_mode cct_cmt430b19n00_mode = {
+	.clock = 9000,
+	.hdisplay = 480,
+	.hsync_start = 480 + 43,
+	.hsync_end = 480 + 43 + 8,
+	.htotal = 480 + 43 + 8 + 4,
+	.vdisplay = 272,
+	.vsync_start = 272 + 12,
+	.vsync_end = 272 + 12 + 8,
+	.vtotal = 272 + 12 + 8 + 4,
+	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
+};
+
+static const struct panel_desc cct_cmt430b19n00 = {
+	.modes = &cct_cmt430b19n00_mode,
+	.num_modes = 1,
+	.bpc = 8,
+	.size = {
+		.width = 95,
+		.height = 53,
+	},
+	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
+	.connector_type = DRM_MODE_CONNECTOR_DPI,
+};
+
 static const struct drm_display_mode cdtech_s043wq26h_ct7_mode = {
 	.clock = 9000,
 	.hdisplay = 480,
@@ -4402,6 +4428,9 @@ static const struct of_device_id platform_of_match[] = {
 	}, {
 		.compatible = "boe,hv070wsa-100",
 		.data = &boe_hv070wsa
+	}, {
+		.compatible = "cct,cmt430b19n00",
+		.data = &cct_cmt430b19n00,
 	}, {
 		.compatible = "cdtech,s043wq26h-ct7",
 		.data = &cdtech_s043wq26h_ct7,
-- 
2.34.1

Re: [PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support

[Maxime Ripard]

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Hi,

On Mon, Mar 04, 2024 at 05:04:54PM +0100, Jérémie Dautheribes wrote:
> Add support for Crystal Clear Technology CMT430B19N00 4.3" 480x272
> TFT-LCD panel.
> 
> Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
> ---
>  drivers/gpu/drm/panel/panel-simple.c | 29 ++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 20e3df1c59d4..b940220f56e2 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -1457,6 +1457,32 @@ static const struct panel_desc boe_hv070wsa = {
>  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>  };
>  
> +static const struct drm_display_mode cct_cmt430b19n00_mode = {
> +	.clock = 9000,
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 43,
> +	.hsync_end = 480 + 43 + 8,
> +	.htotal = 480 + 43 + 8 + 4,
> +	.vdisplay = 272,
> +	.vsync_start = 272 + 12,
> +	.vsync_end = 272 + 12 + 8,
> +	.vtotal = 272 + 12 + 8 + 4,
> +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +};

Your pixel clock doesn't really match the rest of the timings:

(480 + 43 + 8 + 4) * (272 + 12 + 8 + 4) * 60 = 9501600

So a ~6% deviation.

What does the datasheet say?

Maxime

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Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[Conor Dooley]

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On Mon, Mar 04, 2024 at 05:04:51PM +0100, Jérémie Dautheribes wrote:
> Hello everyone,
> 
> This patch series add support for the Crystal Clear Technology
> CMT430B19N00 4.3" 480x272 TFT-LCD panel.
> It also adds Crystal Clear Technology to vendor-prefixes.yaml.
> 
> Please note that unfortunately there is no public datasheet available
> for this panel.
> 
> Changes in v2:
>   - add link to the Crystal Clear Technology website in commit message, as
>   suggested by Conor Dooley and Neil Armstrong.

You forgot however to add the acks that I gave you for the two
dt-binding patches.

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Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[Rob Herring]

On Mon, Mar 04, 2024 at 07:29:04PM +0000, Conor Dooley wrote:
> On Mon, Mar 04, 2024 at 05:04:51PM +0100, Jérémie Dautheribes wrote:
> > Hello everyone,
> > 
> > This patch series add support for the Crystal Clear Technology
> > CMT430B19N00 4.3" 480x272 TFT-LCD panel.
> > It also adds Crystal Clear Technology to vendor-prefixes.yaml.
> > 
> > Please note that unfortunately there is no public datasheet available
> > for this panel.
> > 
> > Changes in v2:
> >   - add link to the Crystal Clear Technology website in commit message, as
> >   suggested by Conor Dooley and Neil Armstrong.
> 
> You forgot however to add the acks that I gave you for the two
> dt-binding patches.

I was wondering why my scripts said this was already reviewed with that 
missing. Turns out b4 will now check prior versions and add the tags as 
long as the patch-id matches. Neat, but the submitter really has to 
grasp how that all works (knowing if the patch-id changed) as well as 
the maintainer has to use b4, so we can't really rely on it.

Here's b4 debug log:

  new message: 20240223-subtotal-aground-268d135adeff@spud                                                                     
Running git --no-pager patch-id --stable                                                                                       
  found matching patch-id for Re: [PATCH 2/3] dt-bindings: display: simple: add support for Crystal Clear CMT430B19N00         
  new message: 20240229-woven-lively-1d90687b2d03@spud                                                                         
  skipping reply without trailers: 20240229-woven-lively-1d90687b2d03@spud
  new message: 20240223134517.728568-2-jeremie.dautheribes@bootlin.com                                                         
  skipping non-reply: 20240223134517.728568-2-jeremie.dautheribes@bootlin.com                                                  
Analyzing follow-up: Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00 (conor@kernel.org)            
  no trailers found, skipping                                                                                                  
Analyzing follow-up: Re: [PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support (mripard@kernel.org)             
  no trailers found, skipping                                                                                                  
    adding "Acked-by: Conor Dooley <conor.dooley@microchip.com>" from trailer_map to: [PATCH v2 1/3] dt-bindings: Add Crystal C
lear Technology vendor prefix                                                                                                  
    adding "Link: http://www.cct.com.my/" from trailer_map to: [PATCH v2 1/3] dt-bindings: Add Crystal Clear Technology vendor 
prefix                                                                                                                         
    adding "Acked-by: Conor Dooley <conor.dooley@microchip.com>" from trailer_map to: [PATCH v2 2/3] dt-bindings: display: simp
le: add support for Crystal Clear CMT430B19N00                                                                                 
    adding "Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>" from trailer_map to: [PATCH v2 3/3] drm/panel: simple: add
 CMT430B19N00 LCD panel support                                                                                                
    adding "Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>" from trailer_map to: [PATCH v2 3/3] drm/panel: simple: add 
CMT430B19N00 LCD panel support                                                                                                 

Re: [PATCH v2 1/3] dt-bindings: Add Crystal Clear Technology vendor prefix

[Krzysztof Kozlowski]

On 04/03/2024 17:04, Jérémie Dautheribes wrote:
> Update Documentation/devicetree/bindings/vendor-prefixes.yaml to
> include "cct" as a vendor prefix for "Crystal Clear Technology". CCT is
> the vendor of the CMT430B19N00 TFT-LCD panel.
> 
> Link: http://www.cct.com.my/
> Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
> ---

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v2 2/3] dt-bindings: display: simple: add support for Crystal Clear CMT430B19N00

[Krzysztof Kozlowski]

On 04/03/2024 17:04, Jérémie Dautheribes wrote:
> Add Crystal Clear Technology CMT430B19N00 4.3" 480x272 TFT-LCD panel
> compatible string.
> 
> Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
> ---
>  .../devicetree/bindings/display/panel/panel-simple.yaml         | 2 ++
>  1 file changed, 2 insertions(+)

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support

[Jérémie Dautheribes]

Hi Maxime,

On 04/03/2024 17:25, Maxime Ripard wrote:
> Hi,
> 
> On Mon, Mar 04, 2024 at 05:04:54PM +0100, Jérémie Dautheribes wrote:
>> Add support for Crystal Clear Technology CMT430B19N00 4.3" 480x272
>> TFT-LCD panel.
>>
>> Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
>> ---
>>   drivers/gpu/drm/panel/panel-simple.c | 29 ++++++++++++++++++++++++++++
>>   1 file changed, 29 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
>> index 20e3df1c59d4..b940220f56e2 100644
>> --- a/drivers/gpu/drm/panel/panel-simple.c
>> +++ b/drivers/gpu/drm/panel/panel-simple.c
>> @@ -1457,6 +1457,32 @@ static const struct panel_desc boe_hv070wsa = {
>>   	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>>   };
>>   
>> +static const struct drm_display_mode cct_cmt430b19n00_mode = {
>> +	.clock = 9000,
>> +	.hdisplay = 480,
>> +	.hsync_start = 480 + 43,
>> +	.hsync_end = 480 + 43 + 8,
>> +	.htotal = 480 + 43 + 8 + 4,
>> +	.vdisplay = 272,
>> +	.vsync_start = 272 + 12,
>> +	.vsync_end = 272 + 12 + 8,
>> +	.vtotal = 272 + 12 + 8 + 4,
>> +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
>> +};
> 
> Your pixel clock doesn't really match the rest of the timings:
> 
> (480 + 43 + 8 + 4) * (272 + 12 + 8 + 4) * 60 = 9501600
> 
> So a ~6% deviation.
> 
> What does the datasheet say?

Indeed it does not exactly match but the datasheet indicates that the 
typical clock frequency is 9MHz and when this frequency is used, the 
typical values of the other parameters are those we have defined in the 
drm_display_mode structure. I don't see any information about the 
accepted deviation either.

Best regards,

Jérémie

Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[Jérémie Dautheribes]

Hi Conor,

On 04/03/2024 20:29, Conor Dooley wrote:
> On Mon, Mar 04, 2024 at 05:04:51PM +0100, Jérémie Dautheribes wrote:
>> Hello everyone,
>>
>> This patch series add support for the Crystal Clear Technology
>> CMT430B19N00 4.3" 480x272 TFT-LCD panel.
>> It also adds Crystal Clear Technology to vendor-prefixes.yaml.
>>
>> Please note that unfortunately there is no public datasheet available
>> for this panel.
>>
>> Changes in v2:
>>    - add link to the Crystal Clear Technology website in commit message, as
>>    suggested by Conor Dooley and Neil Armstrong.
> 
> You forgot however to add the acks that I gave you for the two
> dt-binding patches.


Oops you are right, I'm sorry. Should I send a v3 containing these acks?

Best regards,

Jérémie

Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[Conor Dooley]

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On Mon, Mar 04, 2024 at 03:24:51PM -0600, Rob Herring wrote:
> On Mon, Mar 04, 2024 at 07:29:04PM +0000, Conor Dooley wrote:
> > On Mon, Mar 04, 2024 at 05:04:51PM +0100, Jérémie Dautheribes wrote:
> > > Hello everyone,
> > > 
> > > This patch series add support for the Crystal Clear Technology
> > > CMT430B19N00 4.3" 480x272 TFT-LCD panel.
> > > It also adds Crystal Clear Technology to vendor-prefixes.yaml.
> > > 
> > > Please note that unfortunately there is no public datasheet available
> > > for this panel.
> > > 
> > > Changes in v2:
> > >   - add link to the Crystal Clear Technology website in commit message, as
> > >   suggested by Conor Dooley and Neil Armstrong.
> > 
> > You forgot however to add the acks that I gave you for the two
> > dt-binding patches.
> 
> I was wondering why my scripts said this was already reviewed with that 
> missing. Turns out b4 will now check prior versions and add the tags as 
> long as the patch-id matches. Neat, but the submitter really has to 
> grasp how that all works (knowing if the patch-id changed) as well as 
> the maintainer has to use b4, so we can't really rely on it.
> 
> Here's b4 debug log:
> 
>   new message: 20240223-subtotal-aground-268d135adeff@spud                                                                     
> Running git --no-pager patch-id --stable                                                                                       
>   found matching patch-id for Re: [PATCH 2/3] dt-bindings: display: simple: add support for Crystal Clear CMT430B19N00         
>   new message: 20240229-woven-lively-1d90687b2d03@spud                                                                         
>   skipping reply without trailers: 20240229-woven-lively-1d90687b2d03@spud
>   new message: 20240223134517.728568-2-jeremie.dautheribes@bootlin.com                                                         
>   skipping non-reply: 20240223134517.728568-2-jeremie.dautheribes@bootlin.com                                                  
> Analyzing follow-up: Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00 (conor@kernel.org)            
>   no trailers found, skipping                                                                                                  
> Analyzing follow-up: Re: [PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support (mripard@kernel.org)             
>   no trailers found, skipping                                                                                                  
>     adding "Acked-by: Conor Dooley <conor.dooley@microchip.com>" from trailer_map to: [PATCH v2 1/3] dt-bindings: Add Crystal C
> lear Technology vendor prefix                                                                                                  

>     adding "Link: http://www.cct.com.my/" from trailer_map to: [PATCH v2 1/3] dt-bindings: Add Crystal Clear Technology vendor 
> prefix                                                                                                                         

This is the other nice thing that b4 does, pick up "non review"
trailers too.

>     adding "Acked-by: Conor Dooley <conor.dooley@microchip.com>" from trailer_map to: [PATCH v2 2/3] dt-bindings: display: simp
> le: add support for Crystal Clear CMT430B19N00                                                                                 
>     adding "Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>" from trailer_map to: [PATCH v2 3/3] drm/panel: simple: add
>  CMT430B19N00 LCD panel support                                                                                                
>     adding "Reviewed-by: Jessica Zhang <quic_jesszhan@quicinc.com>" from trailer_map to: [PATCH v2 3/3] drm/panel: simple: add 
> CMT430B19N00 LCD panel support                                                                                                 

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Re: [PATCH v2 0/3] panel-simple: add support for Crystal Clear CMT430B19N00

[Conor Dooley]

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On Tue, Mar 05, 2024 at 10:48:56AM +0100, Jérémie Dautheribes wrote:
> Hi Conor,
> 
> On 04/03/2024 20:29, Conor Dooley wrote:
> > On Mon, Mar 04, 2024 at 05:04:51PM +0100, Jérémie Dautheribes wrote:
> > > Hello everyone,
> > > 
> > > This patch series add support for the Crystal Clear Technology
> > > CMT430B19N00 4.3" 480x272 TFT-LCD panel.
> > > It also adds Crystal Clear Technology to vendor-prefixes.yaml.
> > > 
> > > Please note that unfortunately there is no public datasheet available
> > > for this panel.
> > > 
> > > Changes in v2:
> > >    - add link to the Crystal Clear Technology website in commit message, as
> > >    suggested by Conor Dooley and Neil Armstrong.
> > 
> > You forgot however to add the acks that I gave you for the two
> > dt-binding patches.
> 
> 
> Oops you are right, I'm sorry. Should I send a v3 containing these acks?

I was going to just provide them here, I just wanted to make sure you
didn't intentionally drop them first. But in the interim you got some
from Krzysztof, making some from me redundant anyway :)
I wouldn't bother adding the forgotten acks or resending, I don't care
about my ack count :)

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Re: [PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support

[Maxime Ripard]

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On Tue, Mar 05, 2024 at 10:46:55AM +0100, Jérémie Dautheribes wrote:
> Hi Maxime,
> 
> On 04/03/2024 17:25, Maxime Ripard wrote:
> > Hi,
> > 
> > On Mon, Mar 04, 2024 at 05:04:54PM +0100, Jérémie Dautheribes wrote:
> > > Add support for Crystal Clear Technology CMT430B19N00 4.3" 480x272
> > > TFT-LCD panel.
> > > 
> > > Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
> > > ---
> > >   drivers/gpu/drm/panel/panel-simple.c | 29 ++++++++++++++++++++++++++++
> > >   1 file changed, 29 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> > > index 20e3df1c59d4..b940220f56e2 100644
> > > --- a/drivers/gpu/drm/panel/panel-simple.c
> > > +++ b/drivers/gpu/drm/panel/panel-simple.c
> > > @@ -1457,6 +1457,32 @@ static const struct panel_desc boe_hv070wsa = {
> > >   	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> > >   };
> > > +static const struct drm_display_mode cct_cmt430b19n00_mode = {
> > > +	.clock = 9000,
> > > +	.hdisplay = 480,
> > > +	.hsync_start = 480 + 43,
> > > +	.hsync_end = 480 + 43 + 8,
> > > +	.htotal = 480 + 43 + 8 + 4,
> > > +	.vdisplay = 272,
> > > +	.vsync_start = 272 + 12,
> > > +	.vsync_end = 272 + 12 + 8,
> > > +	.vtotal = 272 + 12 + 8 + 4,
> > > +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> > > +};
> > 
> > Your pixel clock doesn't really match the rest of the timings:
> > 
> > (480 + 43 + 8 + 4) * (272 + 12 + 8 + 4) * 60 = 9501600
> > 
> > So a ~6% deviation.
> > 
> > What does the datasheet say?
> 
> Indeed it does not exactly match but the datasheet indicates that the
> typical clock frequency is 9MHz and when this frequency is used, the
> typical values of the other parameters are those we have defined in
> the drm_display_mode structure.

It seems weird to me that all the typical timings end up in a
non-typical configuration, but I've seen my fair share of weird
datasheet, so.. yeah.

I guess the best thing to do if you have access to the min/typ/max
timings is to actually use the display_timings structure here and define
all of them.

It at least gives us the opportunity to fix it later on.

> I don't see any information about the accepted deviation either.

It's not only about the panel itself. 6% gives your roughly 56fps when
you meant 60. This can then trip up some applications too. Like if
you're playing a 60fps application, it will either play too fast or
you'll get stutter, depending on how the video playback has been
implemented exactly.

Maxime

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Re: [PATCH v2 3/3] drm/panel: simple: add CMT430B19N00 LCD panel support

[Jérémie Dautheribes]

Hi Maxime,

On 08/03/2024 11:48, Maxime Ripard wrote:
> On Tue, Mar 05, 2024 at 10:46:55AM +0100, Jérémie Dautheribes wrote:
>> Hi Maxime,
>>
>> On 04/03/2024 17:25, Maxime Ripard wrote:
>>> Hi,
>>>
>>> On Mon, Mar 04, 2024 at 05:04:54PM +0100, Jérémie Dautheribes wrote:
>>>> Add support for Crystal Clear Technology CMT430B19N00 4.3" 480x272
>>>> TFT-LCD panel.
>>>>
>>>> Signed-off-by: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>
>>>> ---
>>>>    drivers/gpu/drm/panel/panel-simple.c | 29 ++++++++++++++++++++++++++++
>>>>    1 file changed, 29 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
>>>> index 20e3df1c59d4..b940220f56e2 100644
>>>> --- a/drivers/gpu/drm/panel/panel-simple.c
>>>> +++ b/drivers/gpu/drm/panel/panel-simple.c
>>>> @@ -1457,6 +1457,32 @@ static const struct panel_desc boe_hv070wsa = {
>>>>    	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>>>>    };
>>>> +static const struct drm_display_mode cct_cmt430b19n00_mode = {
>>>> +	.clock = 9000,
>>>> +	.hdisplay = 480,
>>>> +	.hsync_start = 480 + 43,
>>>> +	.hsync_end = 480 + 43 + 8,
>>>> +	.htotal = 480 + 43 + 8 + 4,
>>>> +	.vdisplay = 272,
>>>> +	.vsync_start = 272 + 12,
>>>> +	.vsync_end = 272 + 12 + 8,
>>>> +	.vtotal = 272 + 12 + 8 + 4,
>>>> +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
>>>> +};
>>>
>>> Your pixel clock doesn't really match the rest of the timings:
>>>
>>> (480 + 43 + 8 + 4) * (272 + 12 + 8 + 4) * 60 = 9501600
>>>
>>> So a ~6% deviation.
>>>
>>> What does the datasheet say?
>>
>> Indeed it does not exactly match but the datasheet indicates that the
>> typical clock frequency is 9MHz and when this frequency is used, the
>> typical values of the other parameters are those we have defined in
>> the drm_display_mode structure.
> 
> It seems weird to me that all the typical timings end up in a
> non-typical configuration, but I've seen my fair share of weird
> datasheet, so.. yeah.
> 
> I guess the best thing to do if you have access to the min/typ/max
> timings is to actually use the display_timings structure here and define
> all of them.

Yes, I do have access to these timings, I'm going to implement the 
display_timing structure as you suggested, thank you!

Regards,

Jérémie