linux-kernel - Re: Serial 8250 DMA Broken on OMAP3630

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Date:   Mon, 7 Oct 2019 11:17:26 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Adam Ford <aford173@...il.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Vignesh R <vigneshr@...com>,
        Douglas Anderson <dianders@...omium.org>,
        Tony Lindgren <tony@...mide.com>,
        Yegor Yefremov <yegorslists@...glemail.com>,
        linux-serial@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Serial 8250 DMA Broken on OMAP3630

On Sun, Oct 06, 2019 at 12:04:47PM -0500, Adam Ford wrote:

I think the best one who may shed a light is bigeasy@ (Cc'ed).

> Has anyone else had any issues using the CONFIG_SERIAL_8250_DMA on the OMAP?
> 
> I can use the DMA on the legacy, omap-serial driver, but when I enable
> the DMA on the 8250-omap driver, I get missing frames in Bluetooth.
> 
> The older driver seems to have an ISR that seems to address a variety
> of items compared to the very tiny ISR for 8250-omap.c.
> 
> I am not exactly sure where to start, but if someone has any
> suggestions on how I can troubleshoot, please let me know.  As of now,
> I have to disable CONFIG_SERIAL_8250_DMA to get the Bluetooth
> connected to UART2 operational on a DM3730 at 3,000,000 baud, but it
> appears to work just fine after some patches I just submitted for
> handling RTS/CTS.  The legacy omap-serial driver works fine with DMA.
> 
> adam

-- 
With Best Regards,
Andy Shevchenko