[PATCH v3 5/5] drm: rcar-du: dsi: Fix VCLKSET write

[Tomi Valkeinen]

On 22/08/2022 17:45, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Mon, Aug 22, 2022 at 05:34:01PM +0300, Tomi Valkeinen wrote:
>> From: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
>>
>> rcar_mipi_dsi_startup() writes correct values to VCLKSET, but as it uses
>> or-operation to add the new values to the current value in the register,
>> it should first make sure the fields are cleared.
>>
>> Do this by using rcar_mipi_dsi_write() to write the VCLKSET_CKEN bit to
>> VCLKSET before the rest of the VCLKSET configuration.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas at ideasonboard.com>
>> ---
>>   drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
>> index 06250f2f3499..b60a6d4a5d46 100644
>> --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
>> +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
>> @@ -412,9 +412,10 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi *dsi,
>>   			return ret;
>>   	}
>>   
>> -	/* Enable DOT clock */
>> -	vclkset = VCLKSET_CKEN;
>> -	rcar_mipi_dsi_set(dsi, VCLKSET, vclkset);
>> +	/* Clear VCLKSET and enable DOT clock */
>> +	rcar_mipi_dsi_write(dsi, VCLKSET, VCLKSET_CKEN);
>> +
>> +	vclkset = 0;
>>   
>>   	if (dsi_format == 24)
>>   		vclkset |= VCLKSET_BPP_24;
> 
> You can replace one more set() with a write():

That's true. I'll send a new one.

> diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> index 06250f2f3499..2744ea23e6f6 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> @@ -414,7 +414,7 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi *dsi,
> 
>   	/* Enable DOT clock */
>   	vclkset = VCLKSET_CKEN;
> -	rcar_mipi_dsi_set(dsi, VCLKSET, vclkset);
> +	rcar_mipi_dsi_write(dsi, VCLKSET, vclkset);
> 
>   	if (dsi_format == 24)
>   		vclkset |= VCLKSET_BPP_24;
> @@ -429,7 +429,7 @@ static int rcar_mipi_dsi_startup(struct rcar_mipi_dsi *dsi,
>   	vclkset |= VCLKSET_COLOR_RGB | VCLKSET_DIV(setup_info.div)
>   		|  VCLKSET_LANE(dsi->lanes - 1);
> 
> -	rcar_mipi_dsi_set(dsi, VCLKSET, vclkset);
> +	rcar_mipi_dsi_write(dsi, VCLKSET, vclkset);
> 
>   	/* After setting VCLKSET register, enable VCLKEN */
>   	rcar_mipi_dsi_set(dsi, VCLKEN, VCLKEN_CKEN);
> 
> I'll apply patches 1/5 to 4/5 to my tree already.

I'm not sure if 4 works correctly without 2.

  Tomi