On Tue, Apr 18, 2023 at 3:47 AM Lucas Stach <l.stach@xxxxxxxxxxxxxx> wrote: > > Am Dienstag, dem 18.04.2023 um 10:30 +0200 schrieb Marek Vasut: > > On 4/18/23 04:29, Adam Ford wrote: > > > On Sun, Apr 16, 2023 at 5:08 PM Marek Vasut <marex@xxxxxxx> wrote: > > > > > > > > On 4/15/23 12:41, Adam Ford wrote: > > > > > Fetch the clock rate of "sclk_mipi" (or "pll_clk") instead of > > > > > having an entry in the device tree for samsung,pll-clock-frequency. > > > > > > > > > > Signed-off-by: Adam Ford <aford173@xxxxxxxxx> > > > > > --- > > > > > drivers/gpu/drm/bridge/samsung-dsim.c | 12 ++++++------ > > > > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c > > > > > index 9fec32b44e05..73f0c3fbbdf5 100644 > > > > > --- a/drivers/gpu/drm/bridge/samsung-dsim.c > > > > > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c > > > > > @@ -1744,11 +1744,6 @@ static int samsung_dsim_parse_dt(struct samsung_dsim *dsi) > > > > > struct device_node *node = dev->of_node; > > > > > int ret; > > > > > > > > > > - ret = samsung_dsim_of_read_u32(node, "samsung,pll-clock-frequency", > > > > > - &dsi->pll_clk_rate); > > > > > - if (ret < 0) > > > > > - return ret; > > > > > - > > > > > ret = samsung_dsim_of_read_u32(node, "samsung,burst-clock-frequency", > > > > > &dsi->burst_clk_rate); > > > > > if (ret < 0) > > > > > > > > Does this break compatibility with old samsung DTs ? > > > > > > My goal here was to declutter the device tree stuff and fetch data > > > automatically if possible. What if I changed this to make them > > > optional? If they exist, we can use them, if they don't exist, we > > > could read the clock rate. Would that be acceptable? > > > > If you do not see any potential problem with ignoring the DT property > > altogether, that would be better of course, but I think you cannot do > > that with old DTs, so you should retain backward compatibility fallback, > > yes. What do you think ? > > I'm very much in favor of this patch, but I also think we shouldn't > risk breaking Samsung devices, where we don't now 100% that the input > clock rate provided by the clock driver is correct. > > So I think the right approach is to use "samsung,pll-clock-frequency" > when present in DT and get it from the clock provider otherwise. Then > just remove the property from the DTs where we can validate that the > input clock rate is correct, i.e. all i.MX8M*. I'll update this accordingly when I do a V2 of this series. adam > > Regards, > Lucas
