Hello Neil,

On Wed, Oct 23, 2024 at 10:03:20AM +0200, Neil Armstrong wrote:

On 26/09/2024 16:12, Francesco Dolcini wrote:

...

From: Francesco Dolcini francesco.dolcini@toradex.com

Wait for the command transmission to be completed in the DSI transfer function polling for the dc_start bit to go back to idle state after the transmission is started.

This is documented in the datasheet and failures to do so lead to commands corruption.

Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver") Cc: stable@vger.kernel.org Signed-off-by: Francesco Dolcini francesco.dolcini@toradex.com

---

drivers/gpu/drm/bridge/tc358768.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index 0e8813278a2f..bb1750a3dab0 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -125,6 +125,9 @@ #define TC358768_DSI_CONFW_MODE_CLR (6 << 29) #define TC358768_DSI_CONFW_ADDR_DSI_CONTROL (0x3 << 24) +/* TC358768_DSICMD_TX (0x0600) register */ +#define TC358768_DSI_CMDTX_DC_START BIT(0)

• static const char * const tc358768_supplies[] = { "vddc", "vddmipi", "vddio" };

@@ -229,6 +232,21 @@ static void tc358768_update_bits(struct tc358768_priv *priv, u32 reg, u32 mask, tc358768_write(priv, reg, tmp); } +static void tc358768_dsicmd_tx(struct tc358768_priv *priv) +{

• u32 val;
• /* start transfer */
• tc358768_write(priv, TC358768_DSICMD_TX, TC358768_DSI_CMDTX_DC_START);
• if (priv->error)

• return;
  

• /* wait transfer completion */
• priv->error = regmap_read_poll_timeout(priv->regmap, TC358768_DSICMD_TX, val,

• 			       (val & TC358768_DSI_CMDTX_DC_START) == 0,
  

• 			       100, 100000);
  

+}

• static int tc358768_sw_reset(struct tc358768_priv *priv) { /* Assert Reset */

@@ -516,8 +534,7 @@ static ssize_t tc358768_dsi_host_transfer(struct mipi_dsi_host *host, } }

• /* start transfer */
• tc358768_write(priv, TC358768_DSICMD_TX, 1);

• tc358768_dsicmd_tx(priv); ret = tc358768_clear_error(priv); if (ret)

Look good, I'll leave it here a few days if someone has comments

Just a gently reminder, thanks

Reviewed-by: Neil Armstrong neil.armstrong@linaro.org

Francesco