[PATCH v2 2/3] mfd: atmel-hlcdc: fetch LVDS PLL clock for LVDS display

[Manikandan Muralidharan]

The XLCDC IP supports parallel RGB, MIPI DSI and LVDS Display.
The LCD Generic clock (sys_clk) is used for Parallel RGB and MIPI
displays, while the LVDS PLL clock (lvds_pll_clk) is used for LVDS
displays.Since both the clocks cannot co-exist together in the DT
for a given display, this patch first attempts to retrieve sys_clk
If that fails,it then tries to acquire lvds_pll_clk.

Signed-off-by: Manikandan Muralidharan <manikanda...@microchip.com>
Signed-off-by: Dharma Balasubiramani <dharm...@microchip.com>
---
changes in v2:
- Rephrase the comments, commit message and err logs
- Replace dev_err wwith dev_warn
- Remove Initializing sys_clk and lvds_pll_clk to NULL post
devm_kzalloc() call

---
 drivers/mfd/atmel-hlcdc.c       | 16 ++++++++++++++--
 include/linux/mfd/atmel-hlcdc.h |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/atmel-hlcdc.c b/drivers/mfd/atmel-hlcdc.c
index 4c4e35d404f3..f680392b01ba 100644
--- a/drivers/mfd/atmel-hlcdc.c
+++ b/drivers/mfd/atmel-hlcdc.c
@@ -108,10 +108,22 @@ static int atmel_hlcdc_probe(struct platform_device *pdev)
                return PTR_ERR(hlcdc->periph_clk);
        }
 
+       /*
+        * Retrieve any one of the Main clk required by the LCD to operate:
+        *
+        * LCDC Generic Clock (sys_clk) - Parallel RGB and MIPI displays,
+        * LVDS PLL (lvds_pll_clk)      - LVDS display
+        */
        hlcdc->sys_clk = devm_clk_get(dev, "sys_clk");
        if (IS_ERR(hlcdc->sys_clk)) {
-               dev_err(dev, "failed to get system clock\n");
-               return PTR_ERR(hlcdc->sys_clk);
+               dev_warn(dev,
+                        "failed to get LCDC generic clock, trying for LVDS PLL 
clock instead\n");
+
+               hlcdc->lvds_pll_clk = devm_clk_get(dev, "lvds_pll_clk");
+               if (IS_ERR(hlcdc->lvds_pll_clk)) {
+                       dev_err(dev, "failed to get LVDS PLL clock\n");
+                       return PTR_ERR(hlcdc->lvds_pll_clk);
+               }
        }
 
        hlcdc->slow_clk = devm_clk_get(dev, "slow_clk");
diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
index 80d675a03b39..07c2081867fd 100644
--- a/include/linux/mfd/atmel-hlcdc.h
+++ b/include/linux/mfd/atmel-hlcdc.h
@@ -75,6 +75,7 @@
  */
 struct atmel_hlcdc {
        struct regmap *regmap;
+       struct clk *lvds_pll_clk;
        struct clk *periph_clk;
        struct clk *sys_clk;
        struct clk *slow_clk;
-- 
2.25.1