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Message-ID: <e28f88ca-357b-4751-8b37-c324ff40f9f5@linaro.org>
Date: Wed, 23 Oct 2024 10:03:20 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Francesco Dolcini <francesco@...cini.it>,
Andrzej Hajda <andrzej.hajda@...el.com>, Robert Foss <rfoss@...nel.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: Francesco Dolcini <francesco.dolcini@...adex.com>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Subject: Re: [PATCH v1] drm/bridge: tc358768: Fix DSI command tx
On 26/09/2024 16:12, Francesco Dolcini wrote:
> From: Francesco Dolcini <francesco.dolcini@...adex.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@...r.kernel.org
> Signed-off-by: Francesco Dolcini <francesco.dolcini@...adex.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
Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>
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