archive mirror
 help / color / mirror / Atom feed
From: "Guilherme G. Piccoli" <>
Subject: [PATCH] arm64: dts: qcom: db820c: Improve regulator voltage range and mark it as always-on
Date: Mon, 27 Sep 2021 13:37:45 -0300	[thread overview]
Message-ID: <> (raw)

Commit 2317b87a2a6f ("arm64: dts: qcom: db820c: Add vdd_gfx and tie it into mmcc")
introduced this voltage regulator which seems to be essential for the GPU,
according to the board schematics [0]. The problem is that such commit sets
the regulator min/max voltage range to a static value, which is a bit lower than
the range supported to such regulator [1]. With that, the GPU is not stable
as per my experiments (in a Dragonboard 820c-based board) - I've observed
sudden reboots into a FW bad state.

More than that, my experiment showed that this regulator must be set to
always-on - this idea came from a commit in Linaro's tree, from Rajendra [2].
With the voltage range updated plus set as always-on, the GPU is working
correctly, in a stable fashion.

[0] See page 9 (VDD_GFX), at

[1] See section 3.5.3 (FT-SMPS) in the "PMI8994/PMI8996 Power Management IC",


Cc: Rajendra Nayak <>
Cc: Vinod Koul <>
Fixes: 2317b87a2a6f ("arm64: dts: qcom: db820c: Add vdd_gfx and tie it into mmcc")
Signed-off-by: Guilherme G. Piccoli <>

Hi Andy/Bjorn/all, this patch was tested in 5.14, but I've tested it
in the linux-next tree as well and was able to apply there cleanly.
I'm new in the DTS world, so my apologies in advance for any rookie
mistake - suggestions are appreciated! Thanks in advance for the review,


 arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
index 51e17094d7b1..977842068619 100644
--- a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
+++ b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
@@ -699,8 +699,11 @@ &pmi8994_spmi_regulators {
 	vdd_gfx: s2@1700 {
 		reg = <0x1700 0x100>;
 		regulator-name = "VDD_GFX";
-		regulator-min-microvolt = <980000>;
-		regulator-max-microvolt = <980000>;
+		regulator-min-microvolt = <350000>;
+		regulator-max-microvolt = <1350000>;
+		regulator-always-on;
+		status = "okay";

             reply	other threads:[~2021-09-27 17:05 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 16:37 Guilherme G. Piccoli [this message]
2021-09-27 16:39 ` [PATCH] arm64: dts: qcom: db820c: Improve regulator voltage range and mark it as always-on Guilherme G. Piccoli
2021-09-28  3:01 ` Bjorn Andersson
2021-09-28 21:54   ` Guilherme G. Piccoli
2021-09-28 22:55     ` Bjorn Andersson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).