Re: [PATCH v3 1/2] drm/msm/dsi: Use "ref" fw clock instead of global name for VCO parent

Dmitry Baryshkov
2021-12-15T19:58:00Z

On 11/09/2021 16:19, Marijn Suijten wrote:
> 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 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 this patch intentionally breaks older firmware (DT) that
> relies on the clock to be found globally instead. The only affected
> platform is msm8974 [2] for whose dsi_phy_28nm a .name="xo" fallback is
> left in place to accommodate a more graceful transition period. All
> other platforms had the "ref" clock added to their phy node since its
> inception, or in a followup patch some time after. These patches
> wrongly assumed that the "ref" clock was actively used and have hence
> been listed as "Fixes:" below.
> Furthermore apq8064 was providing the wrong 19.2MHz cxo instead of
> 27MHz pxo clock, which has been addressed in [3].
>
> It is expected that both [2] and [3] are applied to the tree well in
> advance of this patch such that any actual breakage is extremely
> unlikely, but might still occur if kernel upgrades are performed without
> the DT to match. After some time the fallback for msm8974 can be
> removed again as well.
>
> [1]: https://lore.kernel.org/linux-arm-msm/386db1a6-a1cd-3c7d-a88e-dc83f8a1be96@somainline.org/
> [2]: https://lore.kernel.org/linux-arm-msm/20210830175739.143401-1-marijn.suijten@somainline.org/
> [3]: https://lore.kernel.org/linux-arm-msm/20210829203027.276143-2-marijn.suijten@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>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.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",
> + },
> .num_parents = 1,
> .name = vco_name,
> .flags = CLK_IGNORE_UNUSED,
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_14nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_14nm.c
> index ebedbb6c8961..789b08c24d25 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_14nm.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_14nm.c
> @@ -802,7 +802,9 @@ static int pll_14nm_register(struct dsi_pll_14nm *pll_14nm, struct clk_hw **prov
> {
> char clk_name[32], parent[32], vco_name[32];
> struct clk_init_data vco_init = {
> - .parent_names = (const char *[]){ "xo" },
> + .parent_data = &(const struct clk_parent_data) {
> + .fw_name = "ref",
> + },
> .num_parents = 1,
> .name = vco_name,
> .flags = CLK_IGNORE_UNUSED,
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> index eb1b8ff61da1..531c4b65aede 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> @@ -521,7 +521,9 @@ static int pll_28nm_register(struct dsi_pll_28nm *pll_28nm, struct clk_hw **prov
> {
> char clk_name[32], parent1[32], parent2[32], vco_name[32];
> struct clk_init_data vco_init = {
> - .parent_names = (const char *[]){ "xo" },
> + .parent_data = &(const struct clk_parent_data) {
> + .fw_name = "ref", .name = "xo",
> + },
> .num_parents = 1,
> .name = vco_name,
> .flags = CLK_IGNORE_UNUSED,
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm_8960.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm_8960.c
> index aaa37456f4ee..9662cb236468 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm_8960.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm_8960.c
> @@ -385,7 +385,9 @@ static int pll_28nm_register(struct dsi_pll_28nm *pll_28nm, struct clk_hw **prov
> {
> char *clk_name, *parent_name, *vco_name;
> struct clk_init_data vco_init = {
> - .parent_names = (const char *[]){ "pxo" },
> + .parent_data = &(const struct clk_parent_data) {
> + .fw_name = "ref",
> + },
> .num_parents = 1,
> .flags = CLK_IGNORE_UNUSED,
> .ops = &clk_ops_dsi_pll_28nm_vco,
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
> index 9eade6d81a54..1a5abbd9fb76 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
> @@ -588,7 +588,9 @@ static int pll_7nm_register(struct dsi_pll_7nm *pll_7nm, struct clk_hw **provide
> 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 *[]){ "bi_tcxo" },
> + .parent_data = &(const struct clk_parent_data) {
> + .fw_name = "ref",
> + },
> .num_parents = 1,
> .name = vco_name,
> .flags = CLK_IGNORE_UNUSED,
> --
> 2.33.0
>

--
With best wishes
Dmitry