On Mon, Feb 03, 2025 at 11:01:28AM +0100, Maxime Ripard wrote:
> Hi Dmitry,
>
> On Thu, Jan 16, 2025 at 03:08:00AM +0200, Dmitry Baryshkov wrote:
> > On Wed, Jan 15, 2025 at 10:05:36PM +0100, Maxime Ripard wrote:
> > > The TI sn65dsi86 driver follows the drm_encoder->crtc pointer that is
> > > deprecated and shouldn't be used by atomic drivers.
> > >
> > > This was due to the fact that we did't have any other alternative to
> > > retrieve the CRTC pointer. Fortunately, the crtc pointer is now provided
> > > in the bridge state, so we can move to atomic callbacks and drop that
> > > deprecated pointer usage.
> > >
> > > Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/bridge/ti-sn65dsi86.c | 41 ++++++++++++++++++++---------------
> > > 1 file changed, 24 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > index b3d617505dda7d22b38c000fb79de46376adf3f1..c17d9486cf5c36d61eb00af2bdf9ba1b6f890ffd 100644
> > > --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > @@ -242,15 +242,16 @@ static void ti_sn65dsi86_write_u16(struct ti_sn65dsi86 *pdata,
> > > u8 buf[2] = { val & 0xff, val >> 8 };
> > >
> > > regmap_bulk_write(pdata->regmap, reg, buf, ARRAY_SIZE(buf));
> > > }
> > >
> > > -static u32 ti_sn_bridge_get_dsi_freq(struct ti_sn65dsi86 *pdata)
> > > +static u32 ti_sn_bridge_get_dsi_freq(struct ti_sn65dsi86 *pdata,
> > > + struct drm_bridge_state *bridge_state)
> > > {
> > > u32 bit_rate_khz, clk_freq_khz;
> > > struct drm_display_mode *mode =
> > > - &pdata->bridge.encoder->crtc->state->adjusted_mode;
> > > + &bridge_state->crtc->state->adjusted_mode;
> >
> > At least we should document why is it safe to follow the crtc->state.
>
> What do you have in mind there? crtc->state is a pointer that is widely
> used, what is there to document?
If I understand correctly, crtc->state is safe to be used during atomic
callbacks only or if the mutex is being held. However this function is
also being called from ti_sn65dsi86_enable_comms(), which is in turn is
used in ti_sn65dsi86_resume(). Is it safe? Why?
--
With best wishes
Dmitry
