[PATCH 2/6] drm/vc4: Bring HDMI up from power off if necessary.

[Eric Anholt]

If the firmware hadn't brought up HDMI for us, we need to do its
power-on reset sequence (reset HD and and clear its STANDBY bits,
reset HDMI, and leave the PHY disabled).

Signed-off-by: Eric Anholt <e...@anholt.net>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 29 ++++++++++++++++++++++++++++-
 drivers/gpu/drm/vc4/vc4_regs.h |  2 ++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index c49cb44..d189906 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -497,6 +497,16 @@ static int vc4_hdmi_bind(struct device *dev, struct device 
*master, void *data)
                goto err_put_i2c;
        }
 
+       /* This is the rate that is set by the firmware.  The number
+        * needs to be a bit higher than the pixel clock rate
+        * (generally 148.5Mhz).
+        */
+       ret = clk_set_rate(hdmi->hsm_clock, 163682864);
+       if (ret) {
+               DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);
+               goto err_unprepare_pix;
+       }
+
        ret = clk_prepare_enable(hdmi->hsm_clock);
        if (ret) {
                DRM_ERROR("Failed to turn on HDMI state machine clock: %d\n",
@@ -518,7 +528,24 @@ static int vc4_hdmi_bind(struct device *dev, struct device 
*master, void *data)
        vc4->hdmi = hdmi;
 
        /* HDMI core must be enabled. */
-       WARN_ON_ONCE((HD_READ(VC4_HD_M_CTL) & VC4_HD_M_ENABLE) == 0);
+       if (!(HD_READ(VC4_HD_M_CTL) & VC4_HD_M_ENABLE)) {
+               HD_WRITE(VC4_HD_M_CTL, VC4_HD_M_SW_RST);
+               udelay(1);
+               HD_WRITE(VC4_HD_M_CTL, 0);
+
+               HD_WRITE(VC4_HD_M_CTL, VC4_HD_M_ENABLE);
+
+               HDMI_WRITE(VC4_HDMI_SW_RESET_CONTROL,
+                          VC4_HDMI_SW_RESET_HDMI |
+                          VC4_HDMI_SW_RESET_FORMAT_DETECT);
+
+               HDMI_WRITE(VC4_HDMI_SW_RESET_CONTROL, 0);
+
+               /* PHY should be in reset, like
+                * vc4_hdmi_encoder_disable() does.
+                */
+               HDMI_WRITE(VC4_HDMI_TX_PHY_RESET_CTL, 0xf << 16);
+       }
 
        drm_encoder_init(drm, hdmi->encoder, &vc4_hdmi_encoder_funcs,
                         DRM_MODE_ENCODER_TMDS, NULL);
diff --git a/drivers/gpu/drm/vc4/vc4_regs.h b/drivers/gpu/drm/vc4/vc4_regs.h
index 25df20e..31042a4 100644
--- a/drivers/gpu/drm/vc4/vc4_regs.h
+++ b/drivers/gpu/drm/vc4/vc4_regs.h
@@ -456,6 +456,8 @@
 #define VC4_HDMI_TX_PHY_RESET_CTL              0x2c0
 
 #define VC4_HD_M_CTL                           0x00c
+# define VC4_HD_M_REGISTER_FILE_STANDBY                (3 << 6)
+# define VC4_HD_M_RAM_STANDBY                  (3 << 4)
 # define VC4_HD_M_SW_RST                       BIT(2)
 # define VC4_HD_M_ENABLE                       BIT(0)
 
-- 
2.7.0