Re: [PATCH v7, 2/4] drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 20/05/22 04:00, xinlei.lee@mediatek.com ha scritto:
> From: Jitao Shi <jitao.shi@mediatek.com>
> 
> In order to match the changes of "Use the drm_panel_bridge API",
> the poweron/poweroff of dsi is extracted from enable/disable and
> defined as new funcs (atomic_pre_enable/atomic_post_disable).
> 
> Since dsi_poweron is moved from dsi_enable to pre_enable function, in
> order to avoid poweron failure, the operation of dsi register fails to
> cause bus hang. Therefore, the protection mechanism is added to the
> dsi_enable function.
> 
> Fixes: 2dd8075d2185 ("drm/mediatek: mtk_dsi: Use the drm_panel_bridge API")
> 
> Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
> Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
> Reviewed-by: CK Hu <ck.hu@mediatek.com>

Hello Xinlei, CK, maintainers:

This patch is breaking machines that are using a DSI->DisplayPort bridge (like
the ANX7625 chip), but that's not the main issue.

----> I have never given a Reviewed-by tag for this commit <----

It's true I've given my tag for an older version [1] of this one, which was *not*
using atomic_* callbacks and that one worked fine (which is why I gave you
my R-b tag for it).

You have changed commits in this series to use atomic_(pre_)enable callbacks
but kept my tag, which is seriously wrong - and even more, because it's actually
breaking display support for a generous number of Chromebooks upstream.


Please be careful next time and ask for a new review when you make substantial
changes to your commits.


Anyway, I have already sent a fix for this situation, please look at [2].

Regards,
Angelo

[1]: 
https://patchwork.kernel.org/project/linux-mediatek/patch/1649644308-8455-3-git-send-email-xinlei.lee@mediatek.com/

[2]: 
https://lore.kernel.org/lkml/20220721172727.14624-1-angelogioacchino.delregno@collabora.com/T/#u

> ---
>   drivers/gpu/drm/mediatek/mtk_dsi.c | 53 +++++++++++++++++++-----------
>   1 file changed, 34 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index f880136cec09..d9a6b928dba8 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -691,16 +691,6 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
>   	if (--dsi->refcount != 0)
>   		return;
>   
> -	/*
> -	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
> -	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
> -	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
> -	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
> -	 * after dsi is fully set.
> -	 */
> -	mtk_dsi_stop(dsi);
> -
> -	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
>   	mtk_dsi_reset_engine(dsi);
>   	mtk_dsi_lane0_ulp_mode_enter(dsi);
>   	mtk_dsi_clk_ulp_mode_enter(dsi);
> @@ -715,17 +705,9 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
>   
>   static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
>   {
> -	int ret;
> -
>   	if (dsi->enabled)
>   		return;
>   
> -	ret = mtk_dsi_poweron(dsi);
> -	if (ret < 0) {
> -		DRM_ERROR("failed to power on dsi\n");
> -		return;
> -	}
> -
>   	mtk_dsi_set_mode(dsi);
>   	mtk_dsi_clk_hs_mode(dsi, 1);
>   
> @@ -739,7 +721,16 @@ static void mtk_output_dsi_disable(struct mtk_dsi *dsi)
>   	if (!dsi->enabled)
>   		return;
>   
> -	mtk_dsi_poweroff(dsi);
> +	/*
> +	 * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
> +	 * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
> +	 * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
> +	 * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
> +	 * after dsi is fully set.
> +	 */
> +	mtk_dsi_stop(dsi);
> +
> +	mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);
>   
>   	dsi->enabled = false;
>   }
> @@ -776,13 +767,37 @@ static void mtk_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
>   {
>   	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
>   
> +	if (dsi->refcount == 0)
> +		return;
> +
>   	mtk_output_dsi_enable(dsi);
>   }
>   
> +static void mtk_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
> +					     struct drm_bridge_state *old_bridge_state)
> +{
> +	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
> +	int ret;
> +
> +	ret = mtk_dsi_poweron(dsi);
> +	if (ret < 0)
> +		DRM_ERROR("failed to power on dsi\n");
> +}
> +
> +static void mtk_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge,
> +					       struct drm_bridge_state *old_bridge_state)
> +{
> +	struct mtk_dsi *dsi = bridge_to_dsi(bridge);
> +
> +	mtk_dsi_poweroff(dsi);
> +}
> +
>   static const struct drm_bridge_funcs mtk_dsi_bridge_funcs = {
>   	.attach = mtk_dsi_bridge_attach,
>   	.atomic_disable = mtk_dsi_bridge_atomic_disable,
>   	.atomic_enable = mtk_dsi_bridge_atomic_enable,
> +	.atomic_pre_enable = mtk_dsi_bridge_atomic_pre_enable,
> +	.atomic_post_disable = mtk_dsi_bridge_atomic_post_disable,
>   	.mode_set = mtk_dsi_bridge_mode_set,
>   };
>