Re: [RFC RESEND] serial: 8250: fix regression in 8250 uart driver

From: Thorsten Leemhuis
Date: Sat Jul 02 2016 - 07:53:25 EST


On 14.06.2016 18:00, Andy Shevchenko wrote:
> On Tue, 2016-06-14 at 10:27 -0500, dinh.linux@xxxxxxxxxxxxx wrote:
>>> On Mon, 2016-06-13 at 21:59 -0500, Dinh Nguyen wrote:
>>> I suppose this one, i.e. commit dd4e91d538b3 ("dmaengine: slave
>>> means at
>>> least one of DMA_SLAVE, DMA_CYCLIC"), solves the issue.
>> Hmm...that commit didn't seem to fix my issue.
> [â]
>> Does this mean that the 8250_dw.c driver can no longer use DMA?
>
> It means that previously the use of DMA engine whatever was used is not
> correct in your case. There is no issues in UART driver, the issue is in
> DMA controller driver.
>
> I'm working on a quirk that will allow user to enforce PIO mode for
> Rx/Tx or both. In that case if DMA controller can't be fixed you still
> might use DMA for Tx.

What's the status of this issue? Just wondering, as this issue is listed
in my regression reports for 4.7 and it seems nothing much happened for
more than a week now â which is a bad sign as the 4.7 release seems only
a week or two away.

CU, Thorsten