Hi Adam,
Am Montag, dem 15.05.2023 um 18:57 -0500 schrieb Adam Ford:
> Make the pll-clock-frequency optional. If it's present, use it
> to maintain backwards compatibility with existing hardware. If it
> is absent, read clock rate of "sclk_mipi" to determine the rate.
> Since it can be optional, change the message from an error to
> dev_info.
>
> Signed-off-by: Adam Ford <aford...@gmail.com>
> Tested-by: Chen-Yu Tsai <we...@chromium.org>
> Tested-by: Frieder Schrempf <frieder.schre...@kontron.de>
> Reviewed-by: Frieder Schrempf <frieder.schre...@kontron.de>
> ---
> drivers/gpu/drm/bridge/samsung-dsim.c | 23 ++++++++++++++++-------
> 1 file changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
> b/drivers/gpu/drm/bridge/samsung-dsim.c
> index bf4b33d2de76..08266303c261 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1712,11 +1712,11 @@ static const struct mipi_dsi_host_ops
> samsung_dsim_ops = {
> };
>
> static int samsung_dsim_of_read_u32(const struct device_node *np,
> - const char *propname, u32 *out_value)
> + const char *propname, u32 *out_value, bool
> optional)
> {
> int ret = of_property_read_u32(np, propname, out_value);
>
> - if (ret < 0)
> + if (ret < 0 && !optional)
> pr_err("%pOF: failed to get '%s' property\n", np, propname);
>
> return ret;
> @@ -1726,20 +1726,29 @@ static int samsung_dsim_parse_dt(struct samsung_dsim
> *dsi)
> {
> struct device *dev = dsi->dev;
> struct device_node *node = dev->of_node;
> + struct clk *pll_clk;
> int ret;
>
> ret = samsung_dsim_of_read_u32(node, "samsung,pll-clock-frequency",
> - &dsi->pll_clk_rate);
> - if (ret < 0)
> - return ret;
> + &dsi->pll_clk_rate, 1);
> +
> + /* If it doesn't exist, read it from the clock instead of failing */
> + if (ret < 0) {
> + dev_info(dev, "Using sclk_mipi for pll clock frequency\n");
While this is certainly helpful while debugging the driver, I don't
think it warrants a info print. Remove or downgrade to dev_dbg?
On the other hand the changed driver behavior should be documented in
the devicetree binding by moving "samsung,pll-clock-frequency" into the
optional properties and spelling out which clock rate is used when the
property is absent.
Regards,
Lucas
> + pll_clk = devm_clk_get(dev, "sclk_mipi");
> + if (!IS_ERR(pll_clk))
> + dsi->pll_clk_rate = clk_get_rate(pll_clk);
> + else
> + return PTR_ERR(pll_clk);
> + }
>
> ret = samsung_dsim_of_read_u32(node, "samsung,burst-clock-frequency",
> - &dsi->burst_clk_rate);
> + &dsi->burst_clk_rate, 0);
> if (ret < 0)
> return ret;
>
> ret = samsung_dsim_of_read_u32(node, "samsung,esc-clock-frequency",
> - &dsi->esc_clk_rate);
> + &dsi->esc_clk_rate, 0);
> if (ret < 0)
> return ret;
>
