[PATCH v6, 2/4] drm/mediatek: Separate poweron/poweroff from enable/disable and define new funcs

[xinlei.lee]

On Wed, 2022-05-18 at 11:39 +0800, CK Hu wrote:
> Hi, Xinlei:
> 
> On Thu, 2022-05-12 at 14:30 +0800, xinlei.lee at mediatek.com wrote:
> > 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).
> > 
> > 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>
> > ---
> >  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;
> 
> This seems not related to pre_enable()/post_disable(). So separate
> this
> to another patch.
> 
> Regards,
> CK
> 
> > +
> >  	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 CK:
Thanks for your review.

The modification here is related to pre_enable()/post_disable().
Because in the previous dsi_enable function, dsi_poweron will be
executed first and then the dsi register will be operated.
But the current modification will move dsi_poweron to the pre_enable
function, and the pre_enable is of void type, when dsi_poweron fails,
an error log will be printed, but the dsi register will be operated in
dsi_enable later , it may cause bus hang.

Therefore, dsi_poweron is judged in the dsi_enable function to avoid
the above situation.
I'll add that description in the comments on the next edition.

Best Regards!
xinlei