Re: [PATCH v2 1/2] drm/msm/dsi: Use "ref" fw clock instead of global name for VCO parent

[Stephen Boyd <sboyd@kernel.org>]

Quoting Marijn Suijten (2021-08-30 11:24:44)
> All DSI PHY/PLL drivers were referencing their VCO parent clock by a
> global name, most of which don't exist or have been renamed.  These
> clock drivers seem to function fine without that except the 14nm driver
> for the sdm6xx [1].
> 
> At the same time all DTs provide a "ref" clock as per the requirements
> of dsi-phy-common.yaml, but the clock is never used.  This patchset puts
> that clock to use without relying on a global clock name, so that all
> dependencies are explicitly defined in DT (the firmware) in the end.
> 
> Note that msm8974 is the only board not providing this clock, and
> apq8064 was providing the wrong clock (19.2MHz cxo instead of 27MHz
> pxo).  Both have been been addressed in separate patches that are
> supposed to land well in advance of this patchset.
> 
> Furthermore not all board-DTs provided this clock initially but that
> deficiency has been addressed in followup patches (see the Fixes:
> below).  Those commits seem to assume that the clock was used, while
> nothing in history indicates that this "ref" clock was ever retrieved.
> 
> [1]: https://lore.kernel.org/linux-arm-msm/386db1a6-a1cd-3c7d-a88e-dc83f8a1be96@somainline.org/
> 
> Fixes: 79e51645a1dd ("arm64: dts: qcom: msm8916: Set 'xo_board' as ref clock of the DSI PHY")
> Fixes: 6969d1d9c615 ("ARM: dts: qcom-apq8064: Set 'cxo_board' as ref clock of the DSI PHY")
> Fixes: 0c0e72705a33 ("arm64: dts: sdm845: Set 'bi_tcxo' as ref clock of the DSI PHYs")
> Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
> ---
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c      | 4 +++-
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_14nm.c      | 4 +++-
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c      | 4 +++-
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm_8960.c | 4 +++-
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c       | 4 +++-
>  5 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
> index e46b10fc793a..3cbb1f1475e8 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_10nm.c
> @@ -562,7 +562,9 @@ static int pll_10nm_register(struct dsi_pll_10nm *pll_10nm, struct clk_hw **prov
>         char clk_name[32], parent[32], vco_name[32];
>         char parent2[32], parent3[32], parent4[32];
>         struct clk_init_data vco_init = {
> -               .parent_names = (const char *[]){ "xo" },
> +               .parent_data = &(const struct clk_parent_data) {
> +                       .fw_name = "ref",

Please also add .name as the old parent_names value so that newer
kernels can be used without having to use new DT.

> +               },
>                 .num_parents = 1,
>                 .name = vco_name,
>                 .flags = CLK_IGNORE_UNUSED,