drm/mcde: Fix DSI transfers

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>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903170804.17053-1-linus.walleij@linaro.org

diff --git a/drivers/gpu/drm/mcde/mcde_dsi.c b/drivers/gpu/drm/mcde/mcde_dsi.c
index 07f7090d08b37f4b32101b5fe61917a45b24486d..f9c9e32b299c9a60c2f530adad3147b93c862c25 100644 (file)
--- 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 read 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 write 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 %d\n",
+                               rxlen, rdsz);
+                       return -EIO;
+               }
+               /* FIXME: read more than 4 bytes */
+               for (i = 0; i < 4 && i < rxlen; i++)
                        rx[i] = (rddat >> (i * 8)) & 0xff;
                ret = rdsz;
        }