From: Sam Ravnborg <sam@ravnborg.org>
To: Bernard <bernard@vivo.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>,
opensource.kernel@vivo.com, David Airlie <airlied@linux.ie>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
Dave Airlie <airlied@redhat.com>
Subject: Re: Re: [PATCH] gpu/drm/mgag200:remove break after return
Date: Sat, 24 Oct 2020 19:14:57 +0200 [thread overview]
Message-ID: <20201024171457.GA76883@ravnborg.org> (raw)
In-Reply-To: <ADgA6wAcDbnOQfg3AhKb6KoN.3.1603439329788.Hmail.bernard@vivo.com>
Hi Bernard.
On Fri, Oct 23, 2020 at 03:48:49PM +0800, Bernard wrote:
>
>
> From: Thomas Zimmermann <tzimmermann@suse.de>
> Date: 2020-10-23 15:13:30
> To: Bernard Zhao <bernard@vivo.com>,Dave Airlie <airlied@redhat.com>,David Airlie <airlied@linux.ie>,Daniel Vetter <daniel@ffwll.ch>,dri-devel@lists.freedesktop.org,linux-kernel@vger.kernel.org
> Cc: opensource.kernel@vivo.com
> Subject: Re: [PATCH] gpu/drm/mgag200:remove break after return>Hi
> >
> >On 23.10.20 09:00, Bernard Zhao wrote:
> >> In function mgag200_set_pci_regs, there are some switch cases
> >> returned, then break. These break will never run.
> >> This patch is to make the code a bit readable.
> >>
> >> Signed-off-by: Bernard Zhao <bernard@vivo.com>
> >> ---
> >> drivers/gpu/drm/mgag200/mgag200_mode.c | 5 +----
> >> 1 file changed, 1 insertion(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >> index 38672f9e5c4f..de873a5d276e 100644
> >> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> >> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >> @@ -794,20 +794,17 @@ static int mgag200_crtc_set_plls(struct mga_device *mdev, long clock)
> >> case G200_SE_A:
> >> case G200_SE_B:
> >> return mga_g200se_set_plls(mdev, clock);
> >> - break;
> >> case G200_WB:
> >> case G200_EW3:
> >> return mga_g200wb_set_plls(mdev, clock);
> >> - break;
> >> case G200_EV:
> >> return mga_g200ev_set_plls(mdev, clock);
> >> - break;
> >> case G200_EH:
> >> case G200_EH3:
> >> return mga_g200eh_set_plls(mdev, clock);
> >> - break;
> >> case G200_ER:
> >> return mga_g200er_set_plls(mdev, clock);
> >> + default:
> >
> >No default case here. If one of the enum values is not handled by the
> >switch, the compiler should warn about it.
>
> Hi
>
> For this point I was a little confused, about this switch variable "mdev->type", my understanding is that this variable`s value can be certain only when the code is running.
> How does the compiler warn this("If one of the enum values is not handled") before the code runs?
If the switch/case does not include "G200_ER" then the compiler can see
one enum value is missing from the list and can warn.
As a test - Try to drop the default and drop G200_ER - then the
compiler (hopefully) will warn.
Sam
next prev parent reply other threads:[~2020-10-24 17:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 7:00 [PATCH] gpu/drm/mgag200:remove break after return Bernard Zhao
2020-10-23 7:13 ` Thomas Zimmermann
2020-10-23 7:48 ` Bernard
2020-10-23 8:29 ` Thomas Zimmermann
2020-10-24 17:14 ` Sam Ravnborg [this message]
2020-10-27 12:05 ` Re:Re: " Bernard
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=20201024171457.GA76883@ravnborg.org \
--to=sam@ravnborg.org \
--cc=airlied@linux.ie \
--cc=airlied@redhat.com \
--cc=bernard@vivo.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=linux-kernel@vger.kernel.org \
--cc=opensource.kernel@vivo.com \
--cc=tzimmermann@suse.de \
/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;
as well as URLs for NNTP newsgroup(s).