Re: [PATCH] drm/omap: dsi: avoid sending bta sync all the time in writes

[Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>]

Applied against 6.18.31, no dice :)

[   11.617523] [drm] Initialized pvr 1.17.4948957 for 56000000.gpu on 
minor 0
[   11.674652] omapdss_dss 58000000.dss: bound 58001000.dispc (ops 
dispc_component_ops [omapdrm])
[   11.775085] omapdss_dss 58000000.dss: bound 58001000.dispc (ops 
dsi_vc_flush_receive_data [omapdrm])
[   12.222930] omapdss_dss 58000000.dss: bound 58001000.dispc (ops 
dsi_vc_flush_receive_data [omapdrm])
[   12.245117] omapdss_dss 58000000.dss: bound 58001000.dispc (ops 
dsi_vc_flush_receive_data [omapdrm])
[   12.247375] omapdss_dss 58000000.dss: bound 58004000.encoder (ops 
dsi_vc_flush_receive_data [omapdrm])
[   12.249267] omapdss_dss 58000000.dss: bound 58006000.encoder (ops 
dsi_vc_flush_receive_data [omapdrm])
[   12.284729] [drm] Initialized omapdrm 1.0.0 for omapdrm.0 on minor 1
[   12.311981] [drm] Enabling DMM ywrap scrolling
[   12.770385] omapdrm omapdrm.0: atomic complete timeout (pipe 0)!
[   22.901306] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   22.901306] omapdrm omapdrm.0: [drm] *ERROR* [CRTC:67:crtc-0] commit 
wait timed out
[   33.131256] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   33.131378] omapdrm omapdrm.0: [drm] *ERROR* [CONNECTOR:66:DSI-1] 
commit wait timed out
[   43.371307] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   43.371398] omapdrm omapdrm.0: [drm] *ERROR* [PLANE:34:plane-0] 
commit wait timed out
[   43.631408] omapdrm omapdrm.0: atomic complete timeout (pipe 0)!
[   43.692504] omapdrm omapdrm.0: [drm] fb0: omapdrmdrmfb frame buffer 
device
[   54.251342] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   54.251464] omapdrm omapdrm.0: [drm] *ERROR* [CRTC:67:crtc-0] commit 
wait timed out
[   64.491302] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   64.491424] omapdrm omapdrm.0: [drm] *ERROR* [CONNECTOR:66:DSI-1] 
commit wait timed out
[   74.731323] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   74.731445] omapdrm omapdrm.0: [drm] *ERROR* [PLANE:34:plane-0] 
commit wait timed out
[   74.991363] omapdrm omapdrm.0: atomic complete timeout (pipe 0)!
[   85.621307] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   85.621398] omapdrm omapdrm.0: [drm] *ERROR* [CRTC:67:crtc-0] commit 
wait timed out
[   95.851287] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[   95.851379] omapdrm omapdrm.0: [drm] *ERROR* [CONNECTOR:66:DSI-1] 
commit wait timed out
[  106.101257] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[  106.101440] omapdrm omapdrm.0: [drm] *ERROR* [PLANE:34:plane-0] 
commit wait timed out
[  106.371459] omapdrm omapdrm.0: atomic complete timeout (pipe 0)!
[  106.961334] omapdrm omapdrm.0: atomic complete timeout (pipe 0)!
[  141.301269] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[  141.301269] omapdrm omapdrm.0: [drm] *ERROR* [CRTC:67:crtc-0] commit 
wait timed out
[  151.531280] omapdrm omapdrm.0: [drm] *ERROR* flip_done timed out
[  151.531402] omapdrm omapdrm.0: [drm] *ERROR* [CONNECTOR:66:DSI-1] 
commit wait timed out


On 28.05.26 г. 13:16 ч., akemnade@kernel.org wrote:
> From: Andreas Kemnade <andreas@kemnade.info>
> 
> Some chips need configuration commands to be sent first, before they can
> send data. TC358762 for example needs PPI_LPTXTIMECNT configured
> and PPI_STARTPPI set to 1 to be able to transmit anything. To be able to
> configure such chips, do not send bta sync during writes if no acks are
> requested. Instead just wait for the packet to be sent to avoid FIFO
> overflows. There might be more to do about acks, but there seem to be
> virtually no users of that flag.
> 
> This came to light when fiddling with the Epson Moverio BT-200 display
> which consists of 2 TC358762 bridges with SPI funneled through
> to the unknown display chip. With that patch the bridge can be accessed,
> Reading back registers works, when the above-mentioned registers are set.
> 
> Video mode panel at OMAP4 (BT-200) and video mode at OMAP5 was tested.
> 
> Fixes: e70965386353e ("drm/omap: dsi: simplify write function")
> Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> ---
> This was not tested on any command mode display, which IMHO should be
> done.  So droid4 folks: please give it a try
> ---
>   drivers/gpu/drm/omapdrm/dss/dsi.c | 32 +++++++++++++++++++++++---------
>   1 file changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/dsi.c b/drivers/gpu/drm/omapdrm/dss/dsi.c
> index 27fe7bca9e2cf..98362b0157023 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dsi.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dsi.c
> @@ -2194,6 +2194,7 @@ static int dsi_vc_send_null(struct dsi_data *dsi, int vc, int channel)
>   static int dsi_vc_write_common(struct omap_dss_device *dssdev, int vc,
>   			       const struct mipi_dsi_msg *msg)
>   {
> +	DECLARE_COMPLETION_ONSTACK(completion);
>   	struct dsi_data *dsi = to_dsi_data(dssdev);
>   	int r;
>   
> @@ -2205,17 +2206,30 @@ static int dsi_vc_write_common(struct omap_dss_device *dssdev, int vc,
>   	if (r < 0)
>   		return r;
>   
> -	/*
> -	 * TODO: we do not always have to do the BTA sync, for example
> -	 * we can improve performance by setting the update window
> -	 * information without sending BTA sync between the commands.
> -	 * In that case we can return early.
> -	 */
> +	/* wait for IRQ for long packet transmission confirmation */
> +	r = dsi_register_isr_vc(dsi, vc, dsi_completion_handler,
> +			&completion, DSI_VC_IRQ_PACKET_SENT);
> +	if (r)
> +		return r;
>   
> -	r = dsi_vc_send_bta_sync(dssdev, vc);
> -	if (r) {
> -		DSSERR("bta sync failed\n");
> +	if (wait_for_completion_timeout(&completion,
> +			msecs_to_jiffies(500)) == 0)
> +		r = -EIO;
> +
> +	dsi_unregister_isr_vc(dsi, vc, dsi_completion_handler,
> +			      &completion, DSI_VC_IRQ_PACKET_SENT);
> +
> +	if (r)
>   		return r;
> +
> +	/* TODO: find out if more needs to be done for MIPI_DIS_MSG_REQ_ACK */
> +
> +	if (msg->flags & MIPI_DSI_MSG_REQ_ACK) {
> +		r = dsi_vc_send_bta_sync(dssdev, vc);
> +		if (r) {
> +			DSSERR("bta sync failed\n");
> +			return r;
> +		}
>   	}
>   
>   	/* RX_FIFO_NOT_EMPTY */
> 
> ---
> base-commit: e7ae89a0c97ce2b68b0983cd01eda67cf373517d
> change-id: 20260528-vm-upstr-c8e7634ebf56
> 
> Best regards,
> --
> Andreas Kemnade <akemnade@kernel.org>
> 
>