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From: Tony Lindgren <tony@atomide.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Linux OMAP Mailing List <linux-omap@vger.kernel.org>,
	Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] serial: 8250: 8250_omap: Fix possible interrupt storm
Date: Tue, 27 Jul 2021 13:39:05 +0300	[thread overview]
Message-ID: <YP/iSZpJ5AIJV70Z@atomide.com> (raw)
In-Reply-To: <CAHp75Vcxtk0f2KRSL8gh2mz-AYE7Kav6co8N8XMbsvtyLohG5w@mail.gmail.com>

* Andy Shevchenko <andy.shevchenko@gmail.com> [210713 09:14]:
> On Tue, Jul 13, 2021 at 11:54 AM Vignesh Raghavendra <vigneshr@ti.com> wrote:
> > On 7/13/21 1:57 AM, andy@surfacebook.localdomain wrote:
> > > Tue, Jun 22, 2021 at 11:53:38AM +0530, Vignesh Raghavendra kirjoitti:
> 
> ...
> 
> > > https://lore.kernel.org/linux-serial/20170206233000.3021-1-dianders@chromium.org/
> >
> > I am not sure if reading UART_LSR is a good idea in the above patch.
> > Some flags in LSR register are cleared on read (at least that's the case
> > for UARTs on TI SoCs) and thus can result in loss of error/FIFO status
> > information.
> >
> > > https://lore.kernel.org/linux-serial/1440015124-28393-1-git-send-email-california.l.sullivan@intel.com/
> >
> > Looks like this never made it.
> 
> Forgot to react to the above. Yes, they never made it because I
> believe due to the exact reason you mentioned above. Also California
> set up different experiments IIRC and it shows that the problem didn;t
> fully disappear with his approach. But maybe yours will work better
> (at least it's not the first time I have seen it on different hardware
> according to people's contributions).

Not sure if this is the same issue with noisy lines, but see also the
following in case it's related:

[PATCH 2/2] serial: 8250_omap: Handle optional overrun-throttle-ms property

Also available at [0] below.

Regards,

Tony

[0] https://lore.kernel.org/linux-omap/20210727103533.51547-1-tony@atomide.com/T/#m5f9da26c32503f2937d3d5977310ca337fa0cb5a

WARNING: multiple messages have this Message-ID (diff)
From: Tony Lindgren <tony@atomide.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Linux OMAP Mailing List <linux-omap@vger.kernel.org>,
	Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] serial: 8250: 8250_omap: Fix possible interrupt storm
Date: Tue, 27 Jul 2021 13:39:05 +0300	[thread overview]
Message-ID: <YP/iSZpJ5AIJV70Z@atomide.com> (raw)
In-Reply-To: <CAHp75Vcxtk0f2KRSL8gh2mz-AYE7Kav6co8N8XMbsvtyLohG5w@mail.gmail.com>

* Andy Shevchenko <andy.shevchenko@gmail.com> [210713 09:14]:
> On Tue, Jul 13, 2021 at 11:54 AM Vignesh Raghavendra <vigneshr@ti.com> wrote:
> > On 7/13/21 1:57 AM, andy@surfacebook.localdomain wrote:
> > > Tue, Jun 22, 2021 at 11:53:38AM +0530, Vignesh Raghavendra kirjoitti:
> 
> ...
> 
> > > https://lore.kernel.org/linux-serial/20170206233000.3021-1-dianders@chromium.org/
> >
> > I am not sure if reading UART_LSR is a good idea in the above patch.
> > Some flags in LSR register are cleared on read (at least that's the case
> > for UARTs on TI SoCs) and thus can result in loss of error/FIFO status
> > information.
> >
> > > https://lore.kernel.org/linux-serial/1440015124-28393-1-git-send-email-california.l.sullivan@intel.com/
> >
> > Looks like this never made it.
> 
> Forgot to react to the above. Yes, they never made it because I
> believe due to the exact reason you mentioned above. Also California
> set up different experiments IIRC and it shows that the problem didn;t
> fully disappear with his approach. But maybe yours will work better
> (at least it's not the first time I have seen it on different hardware
> according to people's contributions).

Not sure if this is the same issue with noisy lines, but see also the
following in case it's related:

[PATCH 2/2] serial: 8250_omap: Handle optional overrun-throttle-ms property

Also available at [0] below.

Regards,

Tony

[0] https://lore.kernel.org/linux-omap/20210727103533.51547-1-tony@atomide.com/T/#m5f9da26c32503f2937d3d5977310ca337fa0cb5a

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  reply	other threads:[~2021-07-27 10:39 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11 15:19 [PATCH] serial: 8250: 8250_omap: Fix possible interrupt storm Vignesh Raghavendra
2021-05-11 15:19 ` Vignesh Raghavendra
2021-05-13 14:17 ` Greg Kroah-Hartman
2021-05-13 14:17   ` Greg Kroah-Hartman
2021-05-28  5:39   ` Tony Lindgren
2021-05-28  5:39     ` Tony Lindgren
2021-05-28  6:11     ` Vignesh Raghavendra
2021-05-28  6:11       ` Vignesh Raghavendra
2021-05-28  9:00       ` Greg Kroah-Hartman
2021-05-28  9:00         ` Greg Kroah-Hartman
2021-06-22  6:15       ` Jan Kiszka
2021-06-22  6:15         ` Jan Kiszka
2021-06-22  6:23         ` Vignesh Raghavendra
2021-06-22  6:23           ` Vignesh Raghavendra
2021-07-12 20:27           ` andy
2021-07-13  8:54             ` Vignesh Raghavendra
2021-07-13  8:54               ` Vignesh Raghavendra
2021-07-13  9:09               ` Andy Shevchenko
2021-07-13  9:09                 ` Andy Shevchenko
2021-07-13  9:13               ` Andy Shevchenko
2021-07-13  9:13                 ` Andy Shevchenko
2021-07-27 10:39                 ` Tony Lindgren [this message]
2021-07-27 10:39                   ` Tony Lindgren

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