mail archive of the barebox mailing list
 help / color / mirror / Atom feed
From: Lucas Stach <dev@lynxeye.de>
To: barebox@lists.infradead.org
Subject: [PATCH] ARM: imx8mq: reclock ARM PLL to 800MHz
Date: Tue, 29 Dec 2020 21:23:28 +0100	[thread overview]
Message-ID: <20201229202328.13857-1-dev@lynxeye.de> (raw)

The BootROM sets up the ARM PLL to run at 1.6GHz and then uses the
divider after the PLL the achieve a CPU clock rate of 800MHz. New Linux
kernels (>= 5.8) switch to a clock path that bypasses the divider, as
the divider should not be used for CPU clock frequencies >1GHz. If the
BootROM setup is left unchanged this causes the CPU clock to jump to
the full 1.6GHz until CPUfreq takes over and reprograms the PLL. This
rate is outside of the chip specification and leads to crashes.

Fix this by reclocking the ARM PLL to 800MHz.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
 arch/arm/dts/imx8mq.dtsi | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm/dts/imx8mq.dtsi b/arch/arm/dts/imx8mq.dtsi
index ec8347f38fa8..e56cdfe1308e 100644
--- a/arch/arm/dts/imx8mq.dtsi
+++ b/arch/arm/dts/imx8mq.dtsi
@@ -17,7 +17,9 @@
 			  <&clk IMX8MQ_CLK_USDHC2>,
 			  <&clk IMX8MQ_CLK_ENET_AXI>,
 			  <&clk IMX8MQ_CLK_ENET_TIMER>,
-			  <&clk IMX8MQ_CLK_ENET_REF>;
+			  <&clk IMX8MQ_CLK_ENET_REF>,
+			  <&clk IMX8MQ_ARM_PLL>,
+			  <&clk IMX8MQ_CLK_A53_DIV>;
 
 	assigned-clock-parents =  <&clk IMX8MQ_SYS1_PLL_400M>,
 				  <&clk IMX8MQ_SYS1_PLL_400M>,
@@ -29,5 +31,7 @@
 			       <200000000>,
 			       <266000000>,
 			       <25000000>,
-			       <125000000>;
+			       <125000000>,
+			       <800000000>,
+			       <800000000>;
 };
-- 
2.29.2


_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

             reply	other threads:[~2020-12-29 20:24 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-29 20:23 Lucas Stach [this message]
2021-01-05 13:35 ` Sascha Hauer

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:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

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

  git send-email \
    --in-reply-to=20201229202328.13857-1-dev@lynxeye.de \
    --to=dev@lynxeye.de \
    --cc=barebox@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* 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