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

[Laurent Pinchart]

On Tue, Aug 23, 2022 at 01:52:38PM +0300, Tomi Valkeinen wrote:
> 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.

I meant 1/5 to 4/5, not 1/5 and 4/5 :-)

-- 
Regards,

Laurent Pinchart