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Date:   Tue, 22 Mar 2022 18:29:17 +0000
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Subject: Re: [PATCH v2] mailbox: tegra-hsp: Flush whole channel
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From:   Jon Hunter <jonathanh@nvidia.com>
To:     Thierry Reding <thierry.reding@gmail.com>,
        Jassi Brar <jassisinghbrar@gmail.com>
Cc:     linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220302150424.1305301-1-thierry.reding@gmail.com>
 <42f99db6-f450-f2dd-fccd-17868b16b561@nvidia.com>
 <c84a0362-8cb0-2925-5a74-ad9c6c3ffe5f@nvidia.com>
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Jassi,

On 10/03/2022 17:37, Jon Hunter wrote:
> 
> 
> On 10/03/2022 16:51, Jon Hunter wrote:
>> Hi Jassi,
>>
>> On 02/03/2022 15:04, 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.
>>>
>>> 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>
>>> ---
>>> Changes in v2:
>>> - add Fixes: line
>>> - Cc stable
>>>
>>>   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;
>>>           }
>>
>>
>> Any feedback on this? Can we queue this up for v5.18?
> 
> Feel free to add my ...
> 
> Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Any feedback?

Jon

-- 
nvpublic