From: Josh Triplett <josh@joshtriplett.org>
To: "Maciej W. Rozycki" <macro@orcam.me.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>
Cc: Anders Blomdell <anders.blomdell@control.lth.se>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH 0/2] serial: 8250: Let drivers request full 16550A feature probing
Date: Sat, 17 Sep 2022 16:00:59 +0100 [thread overview]
Message-ID: <0B189972-4FD8-4245-BF2F-ADEAB18AAAE0@joshtriplett.org> (raw)
In-Reply-To: <alpine.DEB.2.21.2209162317180.19473@angie.orcam.me.uk>
On September 17, 2022 11:07:18 AM GMT+01:00, "Maciej W. Rozycki" <macro@orcam.me.uk> wrote:
>Hi,
>
> A recent change has added a SERIAL_8250_16550A_VARIANTS option, which
>lets one request the 8250 driver not to probe for 16550A device features
>so as to reduce the driver's device startup time in virtual machines.
>This has turned out problematic to a more recent update for the OxSemi
>Tornado series PCIe devices, whose new baud rate generator handling code
>actually requires switching hardware into the enhanced mode for correct
>operation, which actually requires 16550A device features to have been
>probed for.
>
> This small patch series fixes the issue by letting individual device
>subdrivers to request full 16550A device feature probing by means of a
>flag regardless of the SERIAL_8250_16550A_VARIANTS setting chosen.
>
> The changes have been verified with an OXPCIe952 device, in the native
>UART mode and a 64-bit RISC-V system as well as in the legacy UART mode
>and a 32-bit x86 system.
Seems reasonable to me, as long as the flag is only set by drivers that know they've found their hardware.
next prev parent reply other threads:[~2022-09-17 15:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-17 10:07 Maciej W. Rozycki
2022-09-17 10:07 ` [PATCH 1/2] " Maciej W. Rozycki
2022-09-19 4:42 ` Jiri Slaby
2022-09-19 8:18 ` Maciej W. Rozycki
2022-09-19 10:49 ` Jiri Slaby
2022-09-20 23:35 ` Maciej W. Rozycki
2022-09-17 10:07 ` [PATCH 2/2] serial: 8250: Request full 16550A feature probing for OxSemi PCIe devices Maciej W. Rozycki
2022-09-19 4:44 ` Jiri Slaby
2022-09-19 8:23 ` Maciej W. Rozycki
2022-09-20 23:35 ` Maciej W. Rozycki
2022-09-17 15:00 ` Josh Triplett [this message]
2022-09-18 8:26 ` [PATCH 0/2] serial: 8250: Let drivers request full 16550A feature probing Maciej W. Rozycki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=0B189972-4FD8-4245-BF2F-ADEAB18AAAE0@joshtriplett.org \
--to=josh@joshtriplett.org \
--cc=anders.blomdell@control.lth.se \
--cc=gregkh@linuxfoundation.org \
--cc=jirislaby@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=macro@orcam.me.uk \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®