On Tue, Sep 03, 2019 at 10:11:29AM +0200, Linus Walleij wrote:
> There were bugs in the DSI transfer (read and write) function
> as it was only tested with displays ever needing a single byte
> to be written. Fixed it up and tested so we can now write
> messages of up to 16 bytes and read up to 4 bytes from the
> display.
>
> Tested with a Sony ACX424AKP display: this display now self-
> identifies and can control backlight in command mode.
>
> Reported-by: kbuild test robot <[email protected]>
> Fixes: 5fc537bfd000 ("drm/mcde: Add new driver for ST-Ericsson MCDE")
> Reviewed-by: Stephan Gerhold <[email protected]>
> Signed-off-by: Linus Walleij <[email protected]>
> ---
> ChangeLog v2->v3:
> - Fix an error message to indicate reading error rather than
> writing error.
> - Use the local variable for underflow print.
> - Collected Stephan's reviewed-by.
> ChangeLog v1->v2:
> - Fix a print modifier for dev_err() found by the build robot.
> ---
> drivers/gpu/drm/mcde/mcde_dsi.c | 70 ++++++++++++++++++++++-----------
> 1 file changed, 47 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/mcde/mcde_dsi.c b/drivers/gpu/drm/mcde/mcde_dsi.c
> index 07f7090d08b3..cd261c266f35 100644
> --- a/drivers/gpu/drm/mcde/mcde_dsi.c
> +++ b/drivers/gpu/drm/mcde/mcde_dsi.c
> @@ -178,22 +178,26 @@ static ssize_t mcde_dsi_host_transfer(struct
> mipi_dsi_host *host,
> const u32 loop_delay_us = 10; /* us */
> const u8 *tx = msg->tx_buf;
> u32 loop_counter;
> - size_t txlen;
> + size_t txlen = msg->tx_len;
> + size_t rxlen = msg->rx_len;
> u32 val;
> int ret;
> int i;
>
> - txlen = msg->tx_len;
> - if (txlen > 12) {
> + if (txlen > 16) {
> dev_err(d->dev,
> - "dunno how to write more than 12 bytes yet\n");
> + "dunno how to write more than 16 bytes yet\n");
> + return -EIO;
> + }
> + if (rxlen > 4) {
> + dev_err(d->dev,
> + "dunno how to read more than 4 bytes yet\n");
> return -EIO;
> }
>
> dev_dbg(d->dev,
> - "message to channel %d, %zd bytes",
> - msg->channel,
> - txlen);
> + "message to channel %d, write %zd bytes read %zd bytes\n",
> + msg->channel, txlen, rxlen);
>
> /* Command "nature" */
> if (MCDE_DSI_HOST_IS_READ(msg->type))
> @@ -210,9 +214,7 @@ static ssize_t mcde_dsi_host_transfer(struct
> mipi_dsi_host *host,
> if (mipi_dsi_packet_format_is_long(msg->type))
> val |= DSI_DIRECT_CMD_MAIN_SETTINGS_CMD_LONGNOTSHORT;
> val |= 0 << DSI_DIRECT_CMD_MAIN_SETTINGS_CMD_ID_SHIFT;
> - /* Add one to the length for the MIPI DCS command */
> - val |= txlen
> - << DSI_DIRECT_CMD_MAIN_SETTINGS_CMD_SIZE_SHIFT;
> + val |= txlen << DSI_DIRECT_CMD_MAIN_SETTINGS_CMD_SIZE_SHIFT;
> val |= DSI_DIRECT_CMD_MAIN_SETTINGS_CMD_LP_EN;
> val |= msg->type << DSI_DIRECT_CMD_MAIN_SETTINGS_CMD_HEAD_SHIFT;
> writel(val, d->regs + DSI_DIRECT_CMD_MAIN_SETTINGS);
> @@ -249,17 +251,36 @@ static ssize_t mcde_dsi_host_transfer(struct
> mipi_dsi_host *host,
> writel(1, d->regs + DSI_DIRECT_CMD_SEND);
>
> loop_counter = 1000 * 1000 / loop_delay_us;
> - while (!(readl(d->regs + DSI_DIRECT_CMD_STS) &
> - DSI_DIRECT_CMD_STS_WRITE_COMPLETED)
> - && --loop_counter)
> - usleep_range(loop_delay_us, (loop_delay_us * 3) / 2);
> -
> - if (!loop_counter) {
> - dev_err(d->dev, "DSI write timeout!\n");
> - return -ETIME;
> + if (MCDE_DSI_HOST_IS_READ(msg->type)) {
> + /* Read command */
> + while (!(readl(d->regs + DSI_DIRECT_CMD_STS) &
> + (DSI_DIRECT_CMD_STS_READ_COMPLETED |
> + DSI_DIRECT_CMD_STS_READ_COMPLETED_WITH_ERR))
> + && --loop_counter)
> + usleep_range(loop_delay_us, (loop_delay_us * 3) / 2);
> + if (!loop_counter) {
> + dev_err(d->dev, "DSI write timeout!\n");
It looks like you changed the wrong message.
This one is the "read timeout",
> + return -ETIME;
> + }
> + } else {
> + /* Writing only */
> + while (!(readl(d->regs + DSI_DIRECT_CMD_STS) &
> + DSI_DIRECT_CMD_STS_WRITE_COMPLETED)
> + && --loop_counter)
> + usleep_range(loop_delay_us, (loop_delay_us * 3) / 2);
> +
> + if (!loop_counter) {
> + dev_err(d->dev, "DSI read timeout!\n");
and this one the "write timeout".
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