[Nouveau] [PATCH] gr: fallback to legacy paths during firmware lookup

[Alexandre Courbot]

On 11/02/2016 02:07 PM, Ilia Mirkin wrote:
> On Wed, Nov 2, 2016 at 12:54 AM, Alexandre Courbot <acourbot at nvidia.com> wrote:
>> Look for firmware files using the legacy ("nouveau/nvxx_fucxxxx") path
>> if they cannot be found in the new, "official" path. User setups were
>> broken by the switch, which is bad.
>>
>> There are only 4 firmware files we may want to look up that way, so
>> hardcode them into the lookup function. All new firmware files should
>> use the standard "nvidia/<chip>/gr/" path.
>>
>> Fixes: 8539b37acef7 ("drm/nouveau/gr: use NVIDIA-provided external firmwares")
>> Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
>> ---
>>  drm/nouveau/nvkm/engine/gr/gf100.c | 56 ++++++++++++++++++++++++++++++++++----
>>  1 file changed, 51 insertions(+), 5 deletions(-)
>>
>> diff --git a/drm/nouveau/nvkm/engine/gr/gf100.c b/drm/nouveau/nvkm/engine/gr/gf100.c
>> index 157919c788e6..9e65adbab21c 100644
>> --- a/drm/nouveau/nvkm/engine/gr/gf100.c
>> +++ b/drm/nouveau/nvkm/engine/gr/gf100.c
>> @@ -1756,24 +1756,70 @@ gf100_gr_ = {
>>  };
>>
>>  int
>> +gf100_gr_ctor_fw_legacy(struct gf100_gr *gr, const char *fwname,
>> +                       struct gf100_gr_fuc *fuc)
>> +{
>> +       struct nvkm_subdev *subdev = &gr->base.engine.subdev;
>> +       struct nvkm_device *device = subdev->device;
>> +       const struct firmware *fw;
>> +       char f[32];
>> +       int ret;
>> +
>> +       snprintf(f, sizeof(f), "nouveau/nv%02x_%s", device->chipset, fwname);
>> +       ret = request_firmware(&fw, f, device->dev);
>> +       if (ret) {
>> +               snprintf(f, sizeof(f), "nouveau/%s", fwname);
>> +               ret = request_firmware(&fw, f, device->dev);
>> +               if (ret) {
>> +                       nvkm_error(subdev, "failed to load %s\n", fwname);
>> +                       return ret;
>> +               }
>> +       }
>> +
>> +       fuc->size = fw->size;
>> +       fuc->data = kmemdup(fw->data, fuc->size, GFP_KERNEL);
>> +       release_firmware(fw);
>> +       return (fuc->data != NULL) ? 0 : -ENOMEM;
>> +}
>> +
>> +int
>>  gf100_gr_ctor_fw(struct gf100_gr *gr, const char *fwname,
>>                  struct gf100_gr_fuc *fuc)
>>  {
>>         struct nvkm_subdev *subdev = &gr->base.engine.subdev;
>>         struct nvkm_device *device = subdev->device;
>> +       const char *legacy_fwname = NULL;
>>         const struct firmware *fw;
>>         int ret;
>>
>>         ret = nvkm_firmware_get(device, fwname, &fw);
>> -       if (ret) {
>> +       /* firmware found, success! */
>> +       if (!ret) {
>> +               fuc->size = fw->size;
>> +               fuc->data = kmemdup(fw->data, fuc->size, GFP_KERNEL);
>> +               nvkm_firmware_put(fw);
>> +               return (fuc->data != NULL) ? 0 : -ENOMEM;
>> +       }
>> +
>> +       /* see if this firmware has a legacy path */
>> +       if (!strcmp(fwname, "fecs_inst"))
>> +               legacy_fwname = "fuc409c";
>> +       else if (!strcmp(fwname, "fecs_data"))
>> +               legacy_fwname = "fuc409d";
>> +       else if (!strcmp(fwname, "gpccs_inst"))
>> +               legacy_fwname = "fuc41ac";
>> +       else if (!strcmp(fwname, "gpccs_data"))
>> +               legacy_fwname = "fuc41ad";
> 
> As I mentioned on IRC, I find this strcmp thing a little jarring. It
> should be pretty easy to just pass the legacy fwname into
> gf100_gr_ctor_fw directly - there are only a handful of callers, and
> most would just pass NULL in as the legacy fwname - only the ones in
> gf100.c would pass the "old" names in.

Yeah, that was the original approach actually. I switched to this for
the following reasons:

- We don't want to encourage using this legacy path, hence hiding it
from callers
- There are only 4 possible legacy files - it's ugly but still
manageable and contained in a single function

Of course, if the general consensus is that this is too ugly, it would
be trivial to turn it the way you suggested, so I don't feel too
strongly for one approach over the other.