[PATCH] mailbox: tegra-hsp: Flush whole channel

[PATCH] mailbox: tegra-hsp: Flush whole channel

[Thierry Reding]

From: Pekka Pessi <ppessi@nvidia.com>

The txdone can re-fill the mailbox. Keep polling the mailbox during the
flush until all the messages have been delivered.

Signed-off-by: Pekka Pessi <ppessi@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/mailbox/tegra-hsp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mailbox/tegra-hsp.c b/drivers/mailbox/tegra-hsp.c
index acd0675da681..78f7265039c6 100644
--- a/drivers/mailbox/tegra-hsp.c
+++ b/drivers/mailbox/tegra-hsp.c
@@ -412,6 +412,11 @@ static int tegra_hsp_mailbox_flush(struct mbox_chan *chan,
 		value = tegra_hsp_channel_readl(ch, HSP_SM_SHRD_MBOX);
 		if ((value & HSP_SM_SHRD_MBOX_FULL) == 0) {
 			mbox_chan_txdone(chan, 0);
+
+			/* Wait until channel is empty */
+			if (chan->active_req != NULL)
+				continue;
+
 			return 0;
 		}
 
-- 
2.35.1

Re: [PATCH] mailbox: tegra-hsp: Flush whole channel

[Jon Hunter]

On 14/02/2022 15:32, Thierry Reding wrote:
> From: Pekka Pessi <ppessi@nvidia.com>
> 
> The txdone can re-fill the mailbox. Keep polling the mailbox during the
> flush until all the messages have been delivered.
> 
> Signed-off-by: Pekka Pessi <ppessi@nvidia.com>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>   drivers/mailbox/tegra-hsp.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/mailbox/tegra-hsp.c b/drivers/mailbox/tegra-hsp.c
> index acd0675da681..78f7265039c6 100644
> --- a/drivers/mailbox/tegra-hsp.c
> +++ b/drivers/mailbox/tegra-hsp.c
> @@ -412,6 +412,11 @@ static int tegra_hsp_mailbox_flush(struct mbox_chan *chan,
>   		value = tegra_hsp_channel_readl(ch, HSP_SM_SHRD_MBOX);
>   		if ((value & HSP_SM_SHRD_MBOX_FULL) == 0) {
>   			mbox_chan_txdone(chan, 0);
> +
> +			/* Wait until channel is empty */
> +			if (chan->active_req != NULL)
> +				continue;
> +
>   			return 0;
>   		}
>   


Thanks!

Tested-by: Jon Hunter <jonathanh@nvidia.com>

Maybe worth mentioning that this fixes an annoying issue with the TCU 
(Tegra Combined UART) where the output is getting truncated. I think we 
should add the following fixes tag and mark for stable too.

Fixes: 91b1b1c3da8a ("mailbox: tegra-hsp: Add support for shared mailboxes")

Jon

-- 
nvpublic