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

From: Jon Hunter
Date: Mon Feb 14 2022 - 10:43:01 EST



On 14/02/2022 15:32, Thierry Reding wrote:
From: Pekka Pessi <ppessi@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
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@xxxxxxxxxx>

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

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