Messages in this thread | | | Subject | Re:Re: Re: [PATCH] gpu/drm/mgag200:remove break after return | From | Bernard <> | Date | Tue, 27 Oct 2020 20:05:37 +0800 (GMT+08:00) |
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From: Sam Ravnborg <sam@ravnborg.org> Date: 2020-10-25 01:14:57 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>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.
Hi, Sam & Thomas:
Thank you very much for your kind comments, I learned new useful knowledge. I will resubmit the patch.
BR//Bernard
> Sam
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