[PATCH V3 3/7] drm: bridge: samsung-dsim: Fetch pll-clock-frequency automatically

[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.

Signed-off-by: Adam Ford <aford...@gmail.com>
Tested-by: Chen-Yu Tsai <we...@chromium.org>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c 
b/drivers/gpu/drm/bridge/samsung-dsim.c
index bf4b33d2de76..2dc02a9e37c0 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1726,12 +1726,20 @@ 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;
+
+       /* If it doesn't exist, read it from the clock instead of failing */
+       if (ret < 0) {
+               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);
-- 
2.39.2