[PATCH v1] drm/kmb: Handle DSI clock enable failures

[Yuho Choi]

Disable clocks that were enabled before a later DSI clock fails, and
track whether the complete DSI clock set is enabled so teardown does
not disable partially initialized clocks.

Propagate kmb_dsi_clk_init() failures through the display hardware
initialization path instead of continuing with a partially initialized
DSI device.

Fixes: 98521f4d4b4c ("drm/kmb: Mipi DSI part of the display driver")
Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
Signed-off-by: Yuho Choi <dbgh9...@gmail.com>
---
 drivers/gpu/drm/kmb/kmb_drv.c | 6 +++++-
 drivers/gpu/drm/kmb/kmb_dsi.c | 9 +++++++++
 drivers/gpu/drm/kmb/kmb_dsi.h | 1 +
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/kmb/kmb_drv.c b/drivers/gpu/drm/kmb/kmb_drv.c
index 7c2eb1152fc2..fef76d6781b4 100644
--- a/drivers/gpu/drm/kmb/kmb_drv.c
+++ b/drivers/gpu/drm/kmb/kmb_drv.c
@@ -61,6 +61,8 @@ static int kmb_initialize_clocks(struct kmb_drm_private *kmb, 
struct device *dev
        drm_info(&kmb->drm, "system clk = %d Mhz", kmb->sys_clk_mhz);
 
        ret =  kmb_dsi_clk_init(kmb->kmb_dsi);
+       if (ret)
+               return ret;
 
        /* Set LCD clock to 200 Mhz */
        clk_set_rate(kmb->kmb_clk.clk_lcd, KMB_LCD_DEFAULT_CLK);
@@ -130,7 +132,9 @@ static int kmb_hw_init(struct drm_device *drm, unsigned 
long flags)
                return ret;
 
        /* Enable display clocks */
-       kmb_initialize_clocks(kmb, &pdev->dev);
+       ret = kmb_initialize_clocks(kmb, &pdev->dev);
+       if (ret)
+               return ret;
 
        /* Register irqs here - section 17.3 in databook
         * lists LCD at 79 and 82 for MIPI under MSS CPU -
diff --git a/drivers/gpu/drm/kmb/kmb_dsi.c b/drivers/gpu/drm/kmb/kmb_dsi.c
index 59d0e856392f..07dc4e324426 100644
--- a/drivers/gpu/drm/kmb/kmb_dsi.c
+++ b/drivers/gpu/drm/kmb/kmb_dsi.c
@@ -175,9 +175,14 @@ mipi_hs_freq_range[MIPI_DPHY_DEFAULT_BIT_RATES] = {
 
 static void kmb_dsi_clk_disable(struct kmb_dsi *kmb_dsi)
 {
+       if (!kmb_dsi->dsi_clk_enabled)
+               return;
+
        clk_disable_unprepare(kmb_dsi->clk_mipi);
        clk_disable_unprepare(kmb_dsi->clk_mipi_ecfg);
        clk_disable_unprepare(kmb_dsi->clk_mipi_cfg);
+
+       kmb_dsi->dsi_clk_enabled = false;
 }
 
 void kmb_dsi_host_unregister(struct kmb_dsi *kmb_dsi)
@@ -1494,15 +1499,19 @@ static int kmb_dsi_clk_enable(struct kmb_dsi *kmb_dsi)
        ret = clk_prepare_enable(kmb_dsi->clk_mipi_ecfg);
        if (ret) {
                dev_err(dev, "Failed to enable MIPI_ECFG clock: %d\n", ret);
+               clk_disable_unprepare(kmb_dsi->clk_mipi);
                return ret;
        }
 
        ret = clk_prepare_enable(kmb_dsi->clk_mipi_cfg);
        if (ret) {
                dev_err(dev, "Failed to enable MIPI_CFG clock: %d\n", ret);
+               clk_disable_unprepare(kmb_dsi->clk_mipi_ecfg);
+               clk_disable_unprepare(kmb_dsi->clk_mipi);
                return ret;
        }
 
+       kmb_dsi->dsi_clk_enabled = true;
        dev_info(dev, "SUCCESS : enabled MIPI clocks\n");
        return 0;
 }
diff --git a/drivers/gpu/drm/kmb/kmb_dsi.h b/drivers/gpu/drm/kmb/kmb_dsi.h
index 0faadeb9f1dd..8fafcf0d2a96 100644
--- a/drivers/gpu/drm/kmb/kmb_dsi.h
+++ b/drivers/gpu/drm/kmb/kmb_dsi.h
@@ -76,6 +76,7 @@ struct kmb_dsi {
        struct clk *clk_mipi_ecfg;
        struct clk *clk_mipi_cfg;
        int sys_clk_mhz;
+       bool dsi_clk_enabled;
 };
 
 /* DPHY Tx test codes */
-- 
2.43.0