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Message-ID: <c8a514c9-5e48-b561-4b45-47cde3bdfb34@codeaurora.org>
Date: Wed, 27 May 2020 14:17:32 +0530
From: Sharat Masetty <smasetty@...eaurora.org>
To: Rob Clark <robdclark@...il.com>,
freedreno <freedreno@...ts.freedesktop.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>, dri-devel@...edesktop.org,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Georgi Djakov <georgi.djakov@...aro.org>,
Matthias Kaehlcke <mka@...omium.org>
Cc: viresh.kumar@...aro.org, saravanak@...gle.com,
sibis@...eaurora.org, rnayak@...eaurora.org
Subject: Re: [Freedreno] [PATCH 5/6] drm: msm: a6xx: use dev_pm_opp_set_bw to
set DDR bandwidth
+ more folks
On 5/18/2020 9:55 PM, Rob Clark wrote:
> On Mon, May 18, 2020 at 7:23 AM Jordan Crouse <jcrouse@...eaurora.org> wrote:
>> On Thu, May 14, 2020 at 04:24:18PM +0530, Sharat Masetty wrote:
>>> This patches replaces the previously used static DDR vote and uses
>>> dev_pm_opp_set_bw() to scale GPU->DDR bandwidth along with scaling
>>> GPU frequency.
>>>
>>> Signed-off-by: Sharat Masetty <smasetty@...eaurora.org>
>>> ---
>>> drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 6 +-----
>>> 1 file changed, 1 insertion(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>> index 2d8124b..79433d3 100644
>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>>> @@ -141,11 +141,7 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp)
>>>
>>> gmu->freq = gmu->gpu_freqs[perf_index];
>>>
>>> - /*
>>> - * Eventually we will want to scale the path vote with the frequency but
>>> - * for now leave it at max so that the performance is nominal.
>>> - */
>>> - icc_set_bw(gpu->icc_path, 0, MBps_to_icc(7216));
>>> + dev_pm_opp_set_bw(&gpu->pdev->dev, opp);
>>> }
>> This adds an implicit requirement that all targets need bandwidth settings
>> defined in the OPP or they won't get a bus vote at all. I would prefer that
>> there be an default escape valve but if not you'll need to add
>> bandwidth values for the sdm845 OPP that target doesn't regress.
>>
> it looks like we could maybe do something like:
>
> ret = dev_pm_opp_set_bw(...);
> if (ret) {
> dev_warn_once(dev, "no bandwidth settings");
> icc_set_bw(...);
> }
>
> ?
>
> BR,
> -R
There is a bit of an issue here - Looks like its not possible to two icc
handles to the same path. Its causing double enumeration of the paths
in the icc core and messing up path votes. With [1] Since opp/core
already gets a handle to the icc path as part of table add, drm/msm
could do either
a) Conditionally enumerate gpu->icc_path handle only when pm/opp core
has not got the icc path handle. I could use something like [2] to
determine if should initialize gpu->icc_path*
b) Add peak-opp-configs in 845 dt and mandate all future versions to use
this bindings. With this, I can remove gpu->icc_path from msm/drm
completely and only rely on opp/core for bw voting.
[1] - https://lore.kernel.org/patchwork/cover/1240687/
[2] - https://patchwork.kernel.org/patch/11527573/
Let me know your thoughts
Sharat
>
>> Jordan
>>
>>> unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu)
>>> --
>>> 2.7.4
>>>
>> --
>> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>> _______________________________________________
>> Freedreno mailing list
>> Freedreno@...ts.freedesktop.org
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