Hi Yannick,
Could you please share why you are adding this retry?
Are you trying to solve an issue with the generic interface buffs/fifos
overflow?
I think that it could be nice read the CMD_PKT_STATUS register to ensure
that buffs/fifos are not full or empty before a read or write.
> From: Yannick Fertre <yannick.fer...@st.com>
> Date: Wed, Nov 27, 2019 at 10:23:13
>
> From: Yannick Fertré <yannick.fer...@st.com>
>
> Read the DSI_INT_ST1 status register to check if
> errors occur while reading/writing a command to panel.
> In case of error, the transfer is retried 3 times.
>
> Signed-off-by: Yannick Fertre <yannick.fer...@st.com>
> ---
> drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 99
> +++++++++++++++++++++++----
> 1 file changed, 85 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> index b6e793b..cc806ba 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> @@ -212,6 +212,20 @@
>
> #define DSI_INT_ST0 0xbc
> #define DSI_INT_ST1 0xc0
> +#define GPRXE BIT(12)
> +#define GPRDE BIT(11)
> +#define GPTXE BIT(10)
> +#define GPWRE BIT(9)
> +#define GCWRE BIT(8)
> +#define DPIPLDWE BIT(7)
> +#define EOTPE BIT(6)
> +#define PSE BIT(5)
> +#define CRCE BIT(4)
> +#define ECCME BIT(3)
> +#define ECCSE BIT(2)
> +#define TOLPRX BIT(1)
> +#define TOHSTX BIT(0)
> +
> #define DSI_INT_MSK0 0xc4
> #define DSI_INT_MSK1 0xc8
>
> @@ -397,6 +411,42 @@ static int dw_mipi_dsi_gen_pkt_hdr_write(struct
> dw_mipi_dsi *dsi, u32 hdr_val)
> return 0;
> }
>
> +static int dw_mipi_dsi_read_status(struct dw_mipi_dsi *dsi)
> +{
> + u32 val;
> +
> + val = dsi_read(dsi, DSI_INT_ST1);
> +
> + if (val & GPRXE)
> + DRM_DEBUG_DRIVER("DSI Generic payload receive error\n");
> + if (val & GPRDE)
> + DRM_DEBUG_DRIVER("DSI Generic payload read error\n");
> + if (val & GPTXE)
> + DRM_DEBUG_DRIVER("DSI Generic payload transmit error\n");
> + if (val & GPWRE)
> + DRM_DEBUG_DRIVER("DSI Generic payload write error\n");
> + if (val & GCWRE)
> + DRM_DEBUG_DRIVER("DSI Generic command write error\n");
> + if (val & DPIPLDWE)
> + DRM_DEBUG_DRIVER("DSI DPI payload write error\n");
> + if (val & EOTPE)
> + DRM_DEBUG_DRIVER("DSI EoTp error\n");
> + if (val & PSE)
> + DRM_DEBUG_DRIVER("DSI Packet size error\n");
> + if (val & CRCE)
> + DRM_DEBUG_DRIVER("DSI CRC error\n");
> + if (val & ECCME)
> + DRM_DEBUG_DRIVER("DSI ECC multi-bit error\n");
> + if (val & ECCSE)
> + DRM_DEBUG_DRIVER("DSI ECC single-bit error\n");
> + if (val & TOLPRX)
> + DRM_DEBUG_DRIVER("DSI Timeout low-power reception\n");
> + if (val & TOHSTX)
> + DRM_DEBUG_DRIVER("DSI Timeout high-speed transmission\n");
> +
> + return val;
> +}
> +
> static int dw_mipi_dsi_write(struct dw_mipi_dsi *dsi,
> const struct mipi_dsi_packet *packet)
> {
> @@ -426,6 +476,12 @@ static int dw_mipi_dsi_write(struct dw_mipi_dsi *dsi,
> "failed to get available write payload FIFO\n");
> return ret;
> }
> +
> + val = dw_mipi_dsi_read_status(dsi);
> + if (val) {
> + dev_err(dsi->dev, "dsi status error 0x%0x\n", val);
> + return -EINVAL;
> + }
> }
>
> word = 0;
> @@ -459,6 +515,12 @@ static int dw_mipi_dsi_read(struct dw_mipi_dsi *dsi,
> return ret;
> }
>
> + val = dw_mipi_dsi_read_status(dsi);
> + if (val) {
> + dev_err(dsi->dev, "dsi status error 0x%0x\n", val);
> + return -EINVAL;
> + }
> +
> val = dsi_read(dsi, DSI_GEN_PLD_DATA);
> for (j = 0; j < 4 && j + i < len; j++)
> buf[i + j] = val >> (8 * j);
> @@ -473,6 +535,7 @@ static ssize_t dw_mipi_dsi_host_transfer(struct
> mipi_dsi_host *host,
> struct dw_mipi_dsi *dsi = host_to_dsi(host);
> struct mipi_dsi_packet packet;
> int ret, nb_bytes;
> + int retry = 3;
>
> ret = mipi_dsi_create_packet(&packet, msg);
> if (ret) {
> @@ -484,24 +547,32 @@ static ssize_t dw_mipi_dsi_host_transfer(struct
> mipi_dsi_host *host,
> if (dsi->slave)
> dw_mipi_message_config(dsi->slave, msg);
>
> - ret = dw_mipi_dsi_write(dsi, &packet);
> - if (ret)
> - return ret;
> - if (dsi->slave) {
> - ret = dw_mipi_dsi_write(dsi->slave, &packet);
> + while (retry--) {
> + ret = dw_mipi_dsi_write(dsi, &packet);
> if (ret)
> - return ret;
> - }
> + continue;
>
> - if (msg->rx_buf && msg->rx_len) {
> - ret = dw_mipi_dsi_read(dsi, msg);
> - if (ret)
> - return ret;
> - nb_bytes = msg->rx_len;
> - } else {
> - nb_bytes = packet.size;
> + if (dsi->slave) {
> + ret = dw_mipi_dsi_write(dsi->slave, &packet);
> + if (ret)
> + continue;
> + }
> +
> + if (msg->rx_buf && msg->rx_len) {
> + ret = dw_mipi_dsi_read(dsi, msg);
> + if (ret)
> + continue;
> + nb_bytes = msg->rx_len;
> +
> + } else {
> + nb_bytes = packet.size;
> + }
> + break;
> }
>
> + if (ret)
> + return ret;
> +
> return nb_bytes;
> }
>
> --
> 2.7.4
Angelo Ribeiro
Software Engineer, Synopsys, Inc.
angelo.ribe...@synopsys.com
Work: (+351)220 977 109
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