Re: [PATCH 4/6] drm: bridge: samsung-dsim: Dynamically configure DPHY timing

[Adam Ford]

On Mon, Apr 17, 2023 at 6:53 AM Adam Ford <aford173@xxxxxxxxx> wrote:
>
> On Mon, Apr 17, 2023 at 3:38 AM Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote:
> >
> > Hi Adam,
> >
> > Am Samstag, dem 15.04.2023 um 05:41 -0500 schrieb Adam Ford:
> > > NXP uses a lookup table to determine the various values for
> > > the PHY Timing based on the clock rate in their downstream
> > > kernel.  Since the input clock can be variable, the phy
> > > settings need to be variable too.  Add an additional variable
> > > to the driver data to enable this feature to prevent breaking
> > > boards that don't support it.
> > >
> >
> > I haven't checked if this generates values close to the ones in this
> > table, but I guess it should be worth a try to use
> > phy_mipi_dphy_get_default_config() instead.
>
> I didn't know that was a thing.  I like that idea much better than the
> table.  I just pulled what NXP had and tweaked it to fit the mainline.
> I'll give it a try in the next few days, when I have some more time.

I tried phy_mipi_dphy_get_default_config() and the function return
different values than what NXP's table returns, and the screen doesn't
sync properly.  I will try to figure out the mathematical calculation
to generate the values for this DSIM instead of using a lookup table.

adam
>
> adam
> >
> > Regards,
> > Lucas
> >
> > > Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
> > > ---
> > >  drivers/gpu/drm/bridge/samsung-dsim.c |  85 +++++++--
> > >  drivers/gpu/drm/bridge/samsung-dsim.h | 254 ++++++++++++++++++++++++++
> > >  include/drm/bridge/samsung-dsim.h     |   1 +
> > >  3 files changed, 326 insertions(+), 14 deletions(-)
> > >  create mode 100644 drivers/gpu/drm/bridge/samsung-dsim.h
> > >
> <snip>
> >