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SubjectRe: [PATCH] drm/bridge/synopsys: dsi: Add read feature
Hi,

On Sun, Feb 04, 2018 at 10:31:04PM +0100, Philippe Cornu wrote:
> This patch adds the DCS/GENERIC DSI read feature.
>
> Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
> ---
> Extra notes:
> DSI read tests have been performed with DCS & GENERIC, short & long
> commands, on two different panels.
> The maximum fifo size (32*32-bit = 128 bytes on stm32) has been
> verified too.

Seems OK to me, just comparing with work we've been borrowing from
Rockchip:

https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/863347

(And in fact, it looks much better than that.)

So FWIW:

Reviewed-by: Brian Norris <briannorris@chromium.org>

and thanks a bunch!

Brian

> drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 58 +++++++++++++++++++++------
> 1 file changed, 45 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> index e9422d05e897..65aeb3f78b48 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> @@ -397,18 +397,46 @@ static int dw_mipi_dsi_write(struct dw_mipi_dsi *dsi,
> return dw_mipi_dsi_gen_pkt_hdr_write(dsi, le32_to_cpu(word));
> }
>
> +static int dw_mipi_dsi_read(struct dw_mipi_dsi *dsi,
> + const struct mipi_dsi_msg *msg)
> +{
> + int i, j, ret, len = msg->rx_len;
> + u8 *buf = msg->rx_buf;
> + u32 val;
> +
> + /* Wait end of the read operation */
> + ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
> + val, !(val & GEN_RD_CMD_BUSY),
> + 1000, CMD_PKT_STATUS_TIMEOUT_US);
> + if (ret) {
> + dev_err(dsi->dev, "Timeout during read operation\n");
> + return ret;
> + }
> +
> + for (i = 0; i < len; i += 4) {
> + /* Read fifo must not be empty before all bytes are read */
> + ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
> + val, !(val & GEN_PLD_R_EMPTY),
> + 1000, CMD_PKT_STATUS_TIMEOUT_US);
> + if (ret) {
> + dev_err(dsi->dev, "Read payload FIFO is empty\n");
> + return ret;
> + }
> +
> + val = dsi_read(dsi, DSI_GEN_PLD_DATA);
> + for (j = 0; j < 4 && j + i < len; j++)
> + buf[i + j] = val >> (8 * j);
> + }
> +
> + return ret;
> +}
> +
> static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host,
> const struct mipi_dsi_msg *msg)
> {
> struct dw_mipi_dsi *dsi = host_to_dsi(host);
> struct mipi_dsi_packet packet;
> - int ret;
> -
> - if (msg->rx_buf || msg->rx_len) {
> - /* TODO dw drv improvements: implement read feature */
> - dev_warn(dsi->dev, "read operations not yet implemented\n");
> - return -EINVAL;
> - }
> + int ret, nb_bytes;
>
> ret = mipi_dsi_create_packet(&packet, msg);
> if (ret) {
> @@ -422,12 +450,16 @@ static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host,
> if (ret)
> return ret;
>
> - /*
> - * TODO Only transmitted size is returned as actual driver does
> - * not support dcs/generic reads. Please update return value when
> - * delivering the read feature.
> - */
> - return packet.size;
> + 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;
> + }
> +
> + return nb_bytes;
> }
>
> static const struct mipi_dsi_host_ops dw_mipi_dsi_host_ops = {
> --
> 2.15.1
>

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