Re: [PATCH 02/11] drm/bridge: tc358768: Fix bit updates

[Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>]

On 11/08/2023 19:23, Péter Ujfalusi wrote:
> On 04/08/2023 13:44, Tomi Valkeinen wrote:
> > The driver has a few places where it does:
> >
> > if (thing_is_enabled_in_config)
> > 	update_thing_bit_in_hw()
> >
> > This means that if the thing is _not_ enabled, the bit never gets
> > cleared. This affects the h/vsyncs and continuous DSI clock bits.
>
> I guess the idea was to keep the reset value unless it needs to be flipped.
>
> > Fix the driver to always update the bit.
> >
> > Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver")
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/bridge/tc358768.c | 13 +++++++------
> >   1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
> > index bc97a837955b..b668f77673c3 100644
> > --- a/drivers/gpu/drm/bridge/tc358768.c
> > +++ b/drivers/gpu/drm/bridge/tc358768.c
> > @@ -794,8 +794,8 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
> >   		val |= BIT(i + 1);
> >   	tc358768_write(priv, TC358768_HSTXVREGEN, val);
> >   
> > -	if (!(mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> > -		tc358768_write(priv, TC358768_TXOPTIONCNTRL, 0x1);
> > +	tc358768_write(priv, TC358768_TXOPTIONCNTRL,
> > +		       (mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) ? 0 : BIT(0));
> >   
> >   	/* TXTAGOCNT[26:16] RXTASURECNT[10:0] */
> >   	val = tc358768_to_ns((lptxcnt + 1) * dsibclk_nsk * 4);
> > @@ -861,11 +861,12 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
> >   	tc358768_write(priv, TC358768_DSI_HACT, hact);
> >   
> >   	/* VSYNC polarity */
> > -	if (!(mode->flags & DRM_MODE_FLAG_NVSYNC))
> > -		tc358768_update_bits(priv, TC358768_CONFCTL, BIT(5), BIT(5));
> > +	tc358768_update_bits(priv, TC358768_CONFCTL, BIT(5),
> > +			     (mode->flags & DRM_MODE_FLAG_PVSYNC) ? BIT(5) : 0);
>
> Was this the reverse before and should be:
> (mode->flags & DRM_MODE_FLAG_PVSYNC) ? 0 : BIT(5)

Bit 5 is 1 for active high vsync polarity. The test was previously 
!nvsync, i.e. the same as pvsync.

 Tomi