Re: [PATCH v1 4/5] drm/bridge: tc358768: Disable non-continuous clock mode

[Robert Foss]

On Sun, 3 Oct 2021 at 01:35, Dmitry Osipenko  wrote:
>
> Non-continuous clock mode doesn't work because driver doesn't support it
> properly. The bridge driver programs wrong bitfields that are required by
> the non-continuous mode (BTACNTRL1 register bitfields are swapped in the
> code), but fixing them doesn't help.
>
> Display panel of ASUS Transformer TF700T tablet supports non-continuous
> mode and display doesn't work at all using that mode. There are no
> device-trees that are actively using this DSI bridge in upstream yet,
> so clearly the broken mode wasn't ever tested properly. It's a bit too
> difficult to get LP mode working, hence let's disable the offending mode
> for now and fall back to continuous mode.
>
> Tested-by: Andreas Westman Dorcsak  # Asus TF700T
> Tested-by: Maxim Schwalm  #TF700T
> Signed-off-by: Dmitry Osipenko 
> ---
>  drivers/gpu/drm/bridge/tc358768.c | 10 --
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/tc358768.c 
> b/drivers/gpu/drm/bridge/tc358768.c
> index 5b3f8723bd3d..cfceba5ef3b8 100644
> --- a/drivers/gpu/drm/bridge/tc358768.c
> +++ b/drivers/gpu/drm/bridge/tc358768.c
> @@ -631,6 +631,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
> *bridge)
>  {
> struct tc358768_priv *priv = bridge_to_tc358768(bridge);
> struct mipi_dsi_device *dsi_dev = priv->output.dev;
> +   unsigned long mode_flags = dsi_dev->mode_flags;
> u32 val, val2, lptxcnt, hact, data_type;
> const struct drm_display_mode *mode;
> u32 dsibclk_nsk, dsiclk_nsk, ui_nsk, phy_delay_nsk;
> @@ -638,6 +639,11 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
> *bridge)
> const u32 internal_delay = 40;
> int ret, i;
>
> +   if (mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
> +   dev_warn_once(priv->dev, "Non-continuous mode unimplemented, 
> falling back to continuous\n");
> +   mode_flags &= ~MIPI_DSI_CLOCK_NON_CONTINUOUS;
> +   }
> +
> tc358768_hw_enable(priv);
>
> ret = tc358768_sw_reset(priv);
> @@ -776,7 +782,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
> *bridge)
> val |= BIT(i + 1);
> tc358768_write(priv, TC358768_HSTXVREGEN, val);
>
> -   if (!(dsi_dev->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> +   if (!(mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> tc358768_write(priv, TC358768_TXOPTIONCNTRL, 0x1);
>
> /* TXTAGOCNT[26:16] RXTASURECNT[10:0] */
> @@ -864,7 +870,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
> *bridge)
> if (!(dsi_dev->mode_flags & MIPI_DSI_MODE_LPM))
> val |= TC358768_DSI_CONTROL_TXMD;
>
> -   if (!(dsi_dev->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> +   if (!(mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
> val |= TC358768_DSI_CONTROL_HSCKMD;
>
> if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
> --

Reviewed-by: Robert Foss 

[PATCH v1 4/5] drm/bridge: tc358768: Disable non-continuous clock mode

[Dmitry Osipenko]

Non-continuous clock mode doesn't work because driver doesn't support it
properly. The bridge driver programs wrong bitfields that are required by
the non-continuous mode (BTACNTRL1 register bitfields are swapped in the
code), but fixing them doesn't help.

Display panel of ASUS Transformer TF700T tablet supports non-continuous
mode and display doesn't work at all using that mode. There are no
device-trees that are actively using this DSI bridge in upstream yet,
so clearly the broken mode wasn't ever tested properly. It's a bit too
difficult to get LP mode working, hence let's disable the offending mode
for now and fall back to continuous mode.

Tested-by: Andreas Westman Dorcsak  # Asus TF700T
Tested-by: Maxim Schwalm  #TF700T
Signed-off-by: Dmitry Osipenko 
---
 drivers/gpu/drm/bridge/tc358768.c | 10 --
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358768.c 
b/drivers/gpu/drm/bridge/tc358768.c
index 5b3f8723bd3d..cfceba5ef3b8 100644
--- a/drivers/gpu/drm/bridge/tc358768.c
+++ b/drivers/gpu/drm/bridge/tc358768.c
@@ -631,6 +631,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
*bridge)
 {
struct tc358768_priv *priv = bridge_to_tc358768(bridge);
struct mipi_dsi_device *dsi_dev = priv->output.dev;
+   unsigned long mode_flags = dsi_dev->mode_flags;
u32 val, val2, lptxcnt, hact, data_type;
const struct drm_display_mode *mode;
u32 dsibclk_nsk, dsiclk_nsk, ui_nsk, phy_delay_nsk;
@@ -638,6 +639,11 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
*bridge)
const u32 internal_delay = 40;
int ret, i;
 
+   if (mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) {
+   dev_warn_once(priv->dev, "Non-continuous mode unimplemented, 
falling back to continuous\n");
+   mode_flags &= ~MIPI_DSI_CLOCK_NON_CONTINUOUS;
+   }
+
tc358768_hw_enable(priv);
 
ret = tc358768_sw_reset(priv);
@@ -776,7 +782,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
*bridge)
val |= BIT(i + 1);
tc358768_write(priv, TC358768_HSTXVREGEN, val);
 
-   if (!(dsi_dev->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
+   if (!(mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
tc358768_write(priv, TC358768_TXOPTIONCNTRL, 0x1);
 
/* TXTAGOCNT[26:16] RXTASURECNT[10:0] */
@@ -864,7 +870,7 @@ static void tc358768_bridge_pre_enable(struct drm_bridge 
*bridge)
if (!(dsi_dev->mode_flags & MIPI_DSI_MODE_LPM))
val |= TC358768_DSI_CONTROL_TXMD;
 
-   if (!(dsi_dev->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
+   if (!(mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS))
val |= TC358768_DSI_CONTROL_HSCKMD;
 
if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
-- 
2.32.0