[PATCH] drm/panel: visionox-rm69299: Make use of prepare_prev_first

[PATCH] drm/panel: visionox-rm69299: Make use of prepare_prev_first

[David Heidelberg via B4 Relay]

From: Guido Günther <agx@sigxcpu.org>

The DSI link must be powered up to let panel driver to talk to the panel
during prepare() callback execution. Set the prepare_prev_first flag to
guarantee this.

Fixes: 9e15123eca79 ("drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset")
Signed-off-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 drivers/gpu/drm/panel/panel-visionox-rm69299.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/panel/panel-visionox-rm69299.c b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
index e5e688cf98fdc..0e33454650d13 100644
--- a/drivers/gpu/drm/panel/panel-visionox-rm69299.c
+++ b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
@@ -387,6 +387,7 @@ static int visionox_rm69299_probe(struct mipi_dsi_device *dsi)
 	dsi->format = MIPI_DSI_FMT_RGB888;
 	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_LPM |
 			  MIPI_DSI_CLOCK_NON_CONTINUOUS;
+	ctx->panel.prepare_prev_first = true;
 	ret = mipi_dsi_attach(dsi);
 	if (ret < 0) {
 		dev_err(dev, "dsi attach failed ret = %d\n", ret);

---
base-commit: e6efabc0afca02efa263aba533f35d90117ab283
change-id: 20260415-axolotl-display-715ce416e5c8

Best regards,
-- 
David Heidelberg <david@ixit.cz>

Re: [PATCH] drm/panel: visionox-rm69299: Make use of prepare_prev_first

[Doug Anderson]

Hi,

On Wed, Apr 15, 2026 at 2:30 PM David Heidelberg via B4 Relay
<devnull+david.ixit.cz@kernel.org> wrote:
>
> From: Guido Günther <agx@sigxcpu.org>
>
> The DSI link must be powered up to let panel driver to talk to the panel
> during prepare() callback execution. Set the prepare_prev_first flag to
> guarantee this.
>
> Fixes: 9e15123eca79 ("drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset")
> Signed-off-by: Guido Günther <agx@sigxcpu.org>
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
>  drivers/gpu/drm/panel/panel-visionox-rm69299.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/panel/panel-visionox-rm69299.c b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
> index e5e688cf98fdc..0e33454650d13 100644
> --- a/drivers/gpu/drm/panel/panel-visionox-rm69299.c
> +++ b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
> @@ -387,6 +387,7 @@ static int visionox_rm69299_probe(struct mipi_dsi_device *dsi)
>         dsi->format = MIPI_DSI_FMT_RGB888;
>         dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_LPM |
>                           MIPI_DSI_CLOCK_NON_CONTINUOUS;
> +       ctx->panel.prepare_prev_first = true;

Although it probably doesn't matter tons in practice, it seems like it
would be good form to set this _before_ you call drm_panel_add(). Is
there a reason you didn't do that?

-Doug

Re: [PATCH] drm/panel: visionox-rm69299: Make use of prepare_prev_first

[David Heidelberg]

On 17/04/2026 04:38, Doug Anderson wrote:
> Hi,
> 
> On Wed, Apr 15, 2026 at 2:30 PM David Heidelberg via B4 Relay
> <devnull+david.ixit.cz@kernel.org> wrote:
>>
>> From: Guido Günther <agx@sigxcpu.org>
>>
>> The DSI link must be powered up to let panel driver to talk to the panel
>> during prepare() callback execution. Set the prepare_prev_first flag to
>> guarantee this.
>>
>> Fixes: 9e15123eca79 ("drm/msm/dsi: Stop unconditionally powering up DSI hosts at modeset")
>> Signed-off-by: Guido Günther <agx@sigxcpu.org>
>> Signed-off-by: David Heidelberg <david@ixit.cz>
>> ---
>>   drivers/gpu/drm/panel/panel-visionox-rm69299.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/panel/panel-visionox-rm69299.c b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
>> index e5e688cf98fdc..0e33454650d13 100644
>> --- a/drivers/gpu/drm/panel/panel-visionox-rm69299.c
>> +++ b/drivers/gpu/drm/panel/panel-visionox-rm69299.c
>> @@ -387,6 +387,7 @@ static int visionox_rm69299_probe(struct mipi_dsi_device *dsi)
>>          dsi->format = MIPI_DSI_FMT_RGB888;
>>          dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_LPM |
>>                            MIPI_DSI_CLOCK_NON_CONTINUOUS;
>> +       ctx->panel.prepare_prev_first = true;
> 
> Although it probably doesn't matter tons in practice, it seems like it
> would be good form to set this _before_ you call drm_panel_add(). Is
> there a reason you didn't do that?

Hello Doug,

no good reason, I'll send v2 with moved prepare_prev_first before drm_panel_add().

David>
> -Doug

-- 
David Heidelberg