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

[xinlei.lee]

On Thu, 2022-07-21 at 19:28 +0200, AngeloGioacchino Del Regno wrote:
> Il 20/05/22 04:00, xinlei.lee at mediatek.com ha scritto:
> > From: Jitao Shi <jitao.shi at 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 at mediatek.com>
> > Signed-off-by: Xinlei Lee <xinlei.lee at mediatek.com>
> > Reviewed-by: AngeloGioacchino Del Regno <
> > angelogioacchino.delregno at collabora.com>
> > Reviewed-by: Rex-BC Chen <rex-bc.chen at mediatek.com>
> > Reviewed-by: CK Hu <ck.hu at 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://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek/patch/1649644308-8455-3-git-send-email-xinlei.lee@mediatek.com/__;!!CTRNKA9wMg0ARbw!w_fzKvfOShPFrK2vYxBTHs_hi6kORmXAKzNeFORzxRKuNfk8_8Ogvf3h4bPwfjmukw$
>  
> 
> [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,
> >   };
> >   

Hi Angelo:

I am deeply sorry for the problems caused by this patch. 
I understand what you said. If there are substantial changes, I will 
re-request for review. Thank you again for your help.

Best Regards!
xinlei