[PATCH] fix typo for drmOpenByName

Guo, Yejun yejun.guo at intel.com
Thu May 14 05:38:00 PDT 2015

Thanks  Daniel Kurtz  and Emil Velikov for the reply.

In general, drm APIs are invoked by user mode drivers, but, I want to mimic the behavior of driver in my unit test to create buffer objects. After do some searching, I wrote the following code in my unit test (user mode simple application based on libdrm). It does work in my old system (cannot go back to it and so do not know the exact version), but it failed when porting the unit test based on latest libdrm code. I stepped into function drmOpenByName and thought it is a typo.

    int fd = drmOpen("i915", NULL);
    drm_intel_bufmgr* bufmgr = drm_intel_bufmgr_gem_init(fd, 1024);
   drm_intel_bo * bo = drm_intel_bo_alloc(bufmgr,...);

After read the comment, looks like the above code is not used as expected. (I execute the utest together with X11 is running). 

Back to my original purpose, what's the correct way for me to create bo?   One possible way is to open("/dev/dri/renderDxxx"), but what should I do if the kernel version is too low to has this feature? 


-----Original Message-----
From: djkurtz at google.com [mailto:djkurtz at google.com] On Behalf Of Daniel Kurtz
Sent: Thursday, May 14, 2015 6:53 PM
To: Guo, Yejun
Cc: dri-devel
Subject: Re: [PATCH] fix typo for drmOpenByName

NAK.  The original code is correct.

On Thu, May 14, 2015 at 2:17 PM, Guo Yejun <yejun.guo at intel.com> wrote:
> Signed-off-by: Guo Yejun <yejun.guo at intel.com>
> ---
>  xf86drm.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> diff --git a/xf86drm.c b/xf86drm.c
> index f7c45f8..5e7306e 100644
> --- a/xf86drm.c
> +++ b/xf86drm.c
> @@ -635,9 +635,8 @@ static int drmOpenByName(const char *name, int type)
>                     drmFreeVersion(version);
>                     id = drmGetBusid(fd);
>                     drmMsg("drmGetBusid returned '%s'\n", id ? id : "NULL");
> -                   if (!id || !*id) {
> -                       if (id)
> -                           drmFreeBusid(id);

This code basically says:
If no string was returned (id == NULL), or an empty string (*id == NULL), aka "", then return fd and free id if it was an empty string.

> +                   if (id && *id) {
> +                       drmFreeBusid(id);
>                         return fd;
>                     } else {
>                         drmFreeBusid(id);
> --
> 1.9.1
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