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 lkp@intel.com Fixes: 5fc537bfd000 ("drm/mcde: Add new driver for ST-Ericsson MCDE") Reviewed-by: Stephan Gerhold stephan@gerhold.net Signed-off-by: Linus Walleij linus.walleij@linaro.org --- 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"); + 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"); + return -ETIME; + } }

val = readl(d->regs + DSI_DIRECT_CMD_STS); + if (val & DSI_DIRECT_CMD_STS_READ_COMPLETED_WITH_ERR) { + dev_err(d->dev, "read completed with error\n"); + writel(1, d->regs + DSI_DIRECT_CMD_RD_INIT); + return -EIO; + } if (val & DSI_DIRECT_CMD_STS_ACKNOWLEDGE_WITH_ERR_RECEIVED) { val >>= DSI_DIRECT_CMD_STS_ACK_VAL_SHIFT; dev_err(d->dev, "error during transmission: %04x\n", @@ -269,10 +290,7 @@ static ssize_t mcde_dsi_host_transfer(struct mipi_dsi_host *host,

if (!MCDE_DSI_HOST_IS_READ(msg->type)) { /* Return number of bytes written */ - if (mipi_dsi_packet_format_is_long(msg->type)) - ret = 4 + txlen; - else - ret = 4; + ret = txlen; } else { /* OK this is a read command, get the response */ u32 rdsz; @@ -282,7 +300,13 @@ static ssize_t mcde_dsi_host_transfer(struct mipi_dsi_host *host, rdsz = readl(d->regs + DSI_DIRECT_CMD_RD_PROPERTY); rdsz &= DSI_DIRECT_CMD_RD_PROPERTY_RD_SIZE_MASK; rddat = readl(d->regs + DSI_DIRECT_CMD_RDDAT); - for (i = 0; i < 4 && i < rdsz; i++) + if (rdsz < rxlen) { + dev_err(d->dev, "read error, requested %zd got %zd\n", + msg->rx_len, rxlen); + return -EIO; + } + /* FIXME: read more than 4 bytes */ + for (i = 0; i < 4 && i < rxlen; i++) rx[i] = (rddat >> (i * 8)) & 0xff; ret = rdsz; }