Subject: Re: [PATCH v1 4/4] drm/mediatek: fix possible_crtcs

From: YT Shen <[email-masked]>
Date: Mon, 22 Apr 2019 16:59:19 +0800

Hi Frank,
On Tue, 2019-04-16 at 16:58 +0200, Frank Wunderlich wrote:
> From: Ryder Lee <[email-masked]>
> 
> without this patch there is purple stretched font on fbconsole
> 
> source: http://forum.banana-pi.org/t/kernel-4-19-rc1-for-testers/6618/52
> 
> Signed-off-by: Ryder Lee <[email-masked]>
> Tested-by: Frank Wunderlich <[email-masked]>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 5d333138f913..c171b01f77e0 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -610,7 +610,7 @@ static int mtk_dpi_bind(struct device *dev, struct device *master, void *data)
>  	drm_encoder_helper_add(&dpi->encoder, &mtk_dpi_encoder_helper_funcs);
> 
>  	/* Currently DPI0 is fixed to be driven by OVL1 */
> -	dpi->encoder.possible_crtcs = BIT(1);
> +	dpi->encoder.possible_crtcs = BIT(0)|BIT(1);
This patch is not a good solution.

The solution should find the components in the arrays to determine the
correct crtcs, not just set all available bits.  You see the problem
because the hardware connections(BIT0) is not the same as driver
reports(BIT1 changed to BIT0|BIT1, but BIT1 is not supported).

Regards,
yt.shen

> 
>  	ret = drm_bridge_attach(&dpi->encoder, dpi->bridge, NULL);
>  	if (ret) {
> --
> 2.17.1
> 
> 
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