linux-kernel - [PATCH 4/4] drm/panfrost: Set regulators on/off during system sleep on MediaTek SoCs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231030132257.85379-5-angelogioacchino.delregno@collabora.com>
Date:   Mon, 30 Oct 2023 14:22:57 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     boris.brezillon@...labora.com
Cc:     robh@...nel.org, steven.price@....com,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        wenst@...omium.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, kernel@...labora.com
Subject: [PATCH 4/4] drm/panfrost: Set regulators on/off during system sleep on MediaTek SoCs

All of the MediaTek SoCs supported by Panfrost can completely cut power
to the GPU during full system sleep without any user-noticeable delay
in the resume operation, as shown by measurements taken on multiple
MediaTek SoCs.

As an example, for MT8195 - a "before" with only runtime PM operations
(so, without turning on/off regulators), and an "after" executing full
system sleep .resume() handler (.resume() -> .runtime_resume() -> done):

Average Panfrost-only system sleep resume time, before: 114186ns
Average Panfrost-only system sleep resume time, after:  189684ns

Keep in mind that this additional ~0,075ms delay happens only in resume
from a full system suspend, and not in runtime PM operations, hence it
is acceptable.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/gpu/drm/panfrost/panfrost_drv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index 82f3c5fe9c58..f63382d9ab04 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -734,7 +734,7 @@ static const struct panfrost_compatible mediatek_mt8183_b_data = {
 	.supply_names = mediatek_mt8183_b_supplies,
 	.num_pm_domains = ARRAY_SIZE(mediatek_mt8183_pm_domains),
 	.pm_domain_names = mediatek_mt8183_pm_domains,
-	.pm_features = BIT(GPU_PM_CLK_DIS),
+	.pm_features = BIT(GPU_PM_CLK_DIS) | BIT(GPU_PM_VREG_OFF),
 };
 
 static const char * const mediatek_mt8186_pm_domains[] = { "core0", "core1" };
@@ -743,7 +743,7 @@ static const struct panfrost_compatible mediatek_mt8186_data = {
 	.supply_names = mediatek_mt8183_b_supplies,
 	.num_pm_domains = ARRAY_SIZE(mediatek_mt8186_pm_domains),
 	.pm_domain_names = mediatek_mt8186_pm_domains,
-	.pm_features = BIT(GPU_PM_CLK_DIS),
+	.pm_features = BIT(GPU_PM_CLK_DIS) | BIT(GPU_PM_VREG_OFF),
 };
 
 static const char * const mediatek_mt8192_supplies[] = { "mali", NULL };
@@ -754,7 +754,7 @@ static const struct panfrost_compatible mediatek_mt8192_data = {
 	.supply_names = mediatek_mt8192_supplies,
 	.num_pm_domains = ARRAY_SIZE(mediatek_mt8192_pm_domains),
 	.pm_domain_names = mediatek_mt8192_pm_domains,
-	.pm_features = BIT(GPU_PM_CLK_DIS),
+	.pm_features = BIT(GPU_PM_CLK_DIS) | BIT(GPU_PM_VREG_OFF),
 };
 
 static const struct of_device_id dt_match[] = {
-- 
2.42.0