From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Jiri Slaby <jirislaby@kernel.org>, Randy Wright <rwright@hpe.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
Subject: Re: [PATCH v1 3/4] serial: 8250_pci: Always try MSI/MSI-X
Date: Wed, 14 Jul 2021 12:15:25 +0300 [thread overview]
Message-ID: <CAHp75VeuG08M9nURpEmW79euKSJkYvLnFiUe+6cGpRHL4zUOfw@mail.gmail.com> (raw)
In-Reply-To: <9af24b96-8119-7ccf-f0d0-d725af80aa0b@kernel.org>
On Wed, Jul 14, 2021 at 9:55 AM Jiri Slaby <jirislaby@kernel.org> wrote:
>
> On 13. 07. 21, 12:40, Andy Shevchenko wrote:
> > There is no need to try MSI/MSI-X only on selected devices.
> > If MSI is not supported while neing advertised it means device
>
> being
>
> > is broken and we rather introduce a list of such devices which
> > hopefully will be small or never appear.
>
> Hmm, have you checked the commit which introduced the whitelist?
Nope, my bad.
> Nevertheless, this needs to handled with care: while many 8250 devices
> actually claim to support MSI(-X) interrupts it should not be
> enabled be
> default. I had at least one device in my hands with broken MSI
> implementation.
>
> So better introduce a whitelist with devices that are known to support
> MSI(-X) interrupts. I tested all devices mentioned in the patch.
Thanks, but I still think that blacklisting is better. All drivers I
have split (or participated in splitting) from 8250_pci have enabled
MSI for the entire subset they serve for.
> You should have at least CCed the author for an input.
Thanks. I also added Randy, who extended the list.
...
> > + pci_set_master(dev);
>
> But bus mastering is not about MSIs.
Strictly speaking it's not, but MSI won't work without DMA.
> I *think* it's still OK, but you
> need to document that in the commit log too.
>
> Actually, why the commit which added this code turns on bus mastering?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-07-14 9:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 10:40 [PATCH v1 1/4] serial: 8250_pci: Refactor the loop in pci_ite887x_init() Andy Shevchenko
2021-07-13 10:40 ` [PATCH v1 2/4] serial: 8250_pci: Get rid of redundant 'else' keyword Andy Shevchenko
2021-07-13 10:40 ` [PATCH v1 3/4] serial: 8250_pci: Always try MSI/MSI-X Andy Shevchenko
2021-07-14 6:54 ` Jiri Slaby
2021-07-14 7:58 ` Jiri Slaby
2021-07-14 9:31 ` Andy Shevchenko
2021-07-14 9:15 ` Andy Shevchenko [this message]
2021-07-14 16:56 ` rwright
2021-07-14 12:49 ` [EXT] " Ralf Ramsauer
2021-07-14 13:35 ` Andy Shevchenko
2021-07-14 16:49 ` Ralf Ramsauer
2021-07-16 13:07 ` Ralf Ramsauer
2021-07-16 15:01 ` Andy Shevchenko
2021-07-16 15:27 ` Ralf Ramsauer
2021-07-16 17:27 ` Andy Shevchenko
2021-07-17 12:44 ` Ralf Ramsauer
2021-07-13 10:40 ` [PATCH v1 4/4] serial: 8250_pci: Replace dev_*() by pci_*() macros Andy Shevchenko
2021-07-13 21:05 ` Joe Perches
2021-07-14 6:57 ` [PATCH v1 1/4] serial: 8250_pci: Refactor the loop in pci_ite887x_init() Jiri Slaby
2021-07-14 12:37 ` Andy Shevchenko
2021-07-14 8:07 ` Dan Carpenter
2021-07-14 10:44 ` Joe Perches
2021-07-14 12:36 ` Andy Shevchenko
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