linux-kernel - Re: [PATCH 02/12] drm/nouveau/timer: skip calibration on GK20A

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Date:	Fri, 11 Apr 2014 16:34:32 +0900
From:	Alexandre Courbot <acourbot@...dia.com>
To:	Ben Skeggs <skeggsb@...il.com>,
	Alexandre Courbot <gnurou@...il.com>
CC:	Thierry Reding <thierry.reding@...il.com>,
	"nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	Ben Skeggs <bskeggs@...hat.com>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH 02/12] drm/nouveau/timer: skip calibration on GK20A

On 04/11/2014 04:31 PM, Ben Skeggs wrote:
> On Fri, Apr 11, 2014 at 12:46 PM, Alexandre Courbot <gnurou@...il.com> wrote:
>> On Wed, Mar 26, 2014 at 1:19 PM, Ben Skeggs <skeggsb@...il.com> wrote:
>>> On Tue, Mar 25, 2014 at 7:54 AM, Thierry Reding
>>> <thierry.reding@...il.com> wrote:
>>>> On Mon, Mar 24, 2014 at 05:42:24PM +0900, Alexandre Courbot wrote:
>>>>> GK20A's timer is directly attached to the system timer and cannot be
>>>>> calibrated. Skip the calibration phase on that chip since the
>>>>> corresponding registers do not exist.
>>>>>
>>>>> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
>>>>> ---
>>>>>   drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c | 19 +++++++++++++------
>>>>>   1 file changed, 13 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c b/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c
>>>>> index c0bdd10358d7..822fe0d8a871 100644
>>>>> --- a/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c
>>>>> +++ b/drivers/gpu/drm/nouveau/core/subdev/timer/nv04.c
>>>>> @@ -185,6 +185,10 @@ nv04_timer_init(struct nouveau_object *object)
>>>>>        if (ret)
>>>>>                return ret;
>>>>>
>>>>> +     /* gk20a does not have the calibration registers */
>>>>> +     if (device->chipset == 0xea)
>>>>> +             goto skip_clk_init;
>>>>
>>>> I'm concerned that this won't scale in the future. Perhaps a better
>>>> solution would be to add a "flags" or "features" field to struct
>>>> nouveau_device along with feature bits such as HAS_CALIBRATION or
>>>> similar.
>>>>
>>>> That way we don't have to touch this code for every new future Tegra
>>>> chip. Unless perhaps if there's a reason to expect things to change in
>>>> newer generations.
>>> I've already handled this in a slightly different way in the tree I'd
>>> previously pointed Alex at (I think!), as I needed to do the same for
>>> GM107.
>>>
>>> Should just be able to use that implementation (so, just change the
>>> probe patch) here too.
>>
>> I will skip this patch and use your implementation then. Btw,
>> shouldn't the source file for the GK20A implementation be named nvea.c
>> instead of gk20a.c?
> For the Maxwell stuff I've been using "gm107" now too.  Since we're
> working with you guys these days it seems better to use the same names
> for things ;)

So would you like us to use the same naming scheme as well? So far all 
my patches use "nvea.c" whenever I need to add code.
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