Hi, On 22/08/2022 16:25, Biju Das wrote:
Hi Tomi, Thanks for the patch.Subject: [PATCH v2 1/4] drm: rcar-du: dsi: Properly stop video mode TX From: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx> The driver does not explicitly stop the video mode transmission when disabling the output. While this doesn't seem to be causing any issues, lets follow the steps described in the documentation and add a rcar_mipi_dsi_stop_video() which stop the video mode transmission. This function will also be used in later patches to stop the video transmission even if the DSI IP is not shut down. Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx> --- drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 29 +++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c index 62f7eb84ab01..7f2be490fcf8 100644 --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c @@ -542,6 +542,34 @@ static int rcar_mipi_dsi_start_video(struct rcar_mipi_dsi *dsi) return 0; } +static void rcar_mipi_dsi_stop_video(struct rcar_mipi_dsi *dsi) { + u32 status; + int ret; + + /* Disable transmission in video mode. */ + rcar_mipi_dsi_clr(dsi, TXVMCR, TXVMCR_EN_VIDEO); + + ret = read_poll_timeout(rcar_mipi_dsi_read, status, + !(status & TXVMSR_ACT), + 2000, 100000, false, dsi, TXVMSR); + if (ret < 0) { + dev_err(dsi->dev, "Failed to disable video transmission\n"); + return; + } + + /* Assert video FIFO clear. */ + rcar_mipi_dsi_set(dsi, TXVMCR, TXVMCR_VFCLR); + + ret = read_poll_timeout(rcar_mipi_dsi_read, status, + !(status & TXVMSR_VFRDY), + 2000, 100000, false, dsi, TXVMSR); + if (ret < 0) { + dev_err(dsi->dev, "Failed to assert video FIFO clear\n"); + return;This return is not required.
That is true, but I'd personally rather keep it there. If the return is removed, I can imagine how easily one could add a new piece of code in the end of the function, not realizing that one also needs to add a return (the one above) so that the code works correctly.
It just feels a bit safer this way. Tomi
