On 13/01/2021 06:07, Nicolas Boichat wrote:
GPUs with more than a single regulator (e.g. G72 on MT8183) will require platform-specific handling for devfreq, for 2 reasons: 1. The opp core (drivers/opp/core.c:_generic_set_opp_regulator) does not support multiple regulators, so we'll need custom handlers. 2. Generally, platforms with 2 regulators have platform-specific constraints on how the voltages should be set (e.g. minimum/maximum voltage difference between them), so we should not just create generic handlers that simply change the voltages without taking care of those constraints.Disable devfreq for now on those GPUs. Signed-off-by: Nicolas Boichat <drink...@chromium.org> Reviewed-by: Tomeu Vizoso <tomeu.viz...@collabora.com>
Thanks for the clarification in the commit message. Reviewed-by: Steven Price <steven.pr...@arm.com>
--- (no changes since v9) Changes in v9: - Explain why devfreq needs to be disabled for GPUs with >1 regulators. Changes in v8: - Use DRM_DEV_INFO instead of ERROR Changes in v7: - Fix GPU ID in commit message Changes in v6: - New change drivers/gpu/drm/panfrost/panfrost_devfreq.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c index f44d28fad085..812cfecdee3b 100644 --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c @@ -92,6 +92,15 @@ int panfrost_devfreq_init(struct panfrost_device *pfdev) struct thermal_cooling_device *cooling; struct panfrost_devfreq *pfdevfreq = &pfdev->pfdevfreq;+ if (pfdev->comp->num_supplies > 1) {+ /* + * GPUs with more than 1 supply require platform-specific handling: + * continue without devfreq + */ + DRM_DEV_INFO(dev, "More than 1 supply is not supported yet\n"); + return 0; + } + opp_table = dev_pm_opp_set_regulators(dev, pfdev->comp->supply_names, pfdev->comp->num_supplies); if (IS_ERR(opp_table)) {
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