From: Pekka Pessi <ppessi@nvidia.com> stable inclusion from stable-v5.10.110 commit 958e9b56de7b8dad732d67b00c632e2ec15c337a bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 60de2d2dc284e0dd1c2c897d08625bde24ef3454 upstream. The txdone can re-fill the mailbox. Keep polling the mailbox during the flush until all the messages have been delivered. This fixes an issue with the Tegra Combined UART (TCU) where output can get truncated under high traffic load. Signed-off-by: Pekka Pessi <ppessi@nvidia.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Fixes: 91b1b1c3da8a ("mailbox: tegra-hsp: Add support for shared mailboxes") Cc: stable@vger.kernel.org Signed-off-by: Thierry Reding <treding@nvidia.com> Reviewed-by: Jon Hunter <jonathanh@nvidia.com> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yu Liao <liaoyu15@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.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 e07091d71986..4895d8074002 100644 --- a/drivers/mailbox/tegra-hsp.c +++ b/drivers/mailbox/tegra-hsp.c @@ -410,6 +410,11 @@ 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; } -- 2.20.1