On Tue, 16 Jul 2024 at 15:32, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
>
> On 16/07/2024 13:20, Dmitry Baryshkov wrote:
> > On Tue, Jul 16, 2024 at 11:05:22AM GMT, Neil Armstrong wrote:
> >> Add the missing CLK_SET_RATE_PARENT for the byte0_div_clk_src
> >> and byte1_div_clk_src, the clock rate should propagate to
> >> the corresponding _clk_src.
> >>
> >> Fixes: 9e939f008338 ("clk: qcom: add the SM8650 Display Clock Controller driver")
> >> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> >> Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> >> ---
> >> drivers/clk/qcom/dispcc-sm8650.c | 2 ++
> >> 1 file changed, 2 insertions(+)
> >
> > This doesn't seem correct, the byte1_div_clk_src is a divisor, so the
> > rate should not be propagated. Other platforms don't set this flag.
> >
>
> Why not ? the disp_cc_mdss_byte1_clk_src has CLK_SET_RATE_PARENT and a div_table,
> and we only pass DISP_CC_MDSS_BYTE1_CLK to the dsi controller.
Yes, the driver sets byte_clk with the proper rate, then it sets
byte_intf_clk, which results in a proper divisor.
If we have CLK_SET_RATE_PARENT for byte1_div_clk_src, then setting
byte_intf_clk rate will also result in a rate change for the byte_clk
rate.
Note, all other platforms don't set that flag for this reason (I think
I had to remove it during sm8450 development for this reason).
--
With best wishes
Dmitry
