[PATCH] arm64: dts: amlogic: g12: bump spdif output drive strength

[PATCH] arm64: dts: amlogic: g12: bump spdif output drive strength

[Jerome Brunet]

Spdif output currently uses a 0.5mA drive strength by default.
While the result depends on how the spdif output is hooked to
rest of the system, this is a bit weak and signal quality
may be poor. This was reported on the vim3l for example.

Increase the drive strength to 3mA, as used for TDM, to be on the
safe side.

Fixes: 649675db939d ("arm64: dts: meson: g12a: add spdifouts")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi
index 138fb18c6480..4057ee808a58 100644
--- a/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi
@@ -987,7 +987,7 @@ spdif_out_h_pins: spdif-out-h {
 						mux {
 							groups = "spdif_out_h";
 							function = "spdif_out";
-							drive-strength-microamp = <500>;
+							drive-strength-microamp = <3000>;
 							bias-disable;
 						};
 					};
@@ -996,7 +996,7 @@ spdif_out_a11_pins: spdif-out-a11 {
 						mux {
 							groups = "spdif_out_a11";
 							function = "spdif_out";
-							drive-strength-microamp = <500>;
+							drive-strength-microamp = <3000>;
 							bias-disable;
 						};
 					};
@@ -1005,7 +1005,7 @@ spdif_out_a13_pins: spdif-out-a13 {
 						mux {
 							groups = "spdif_out_a13";
 							function = "spdif_out";
-							drive-strength-microamp = <500>;
+							drive-strength-microamp = <3000>;
 							bias-disable;
 						};
 					};
@@ -1826,7 +1826,7 @@ spdif_ao_out_pins: spdif-ao-out {
 					mux {
 						groups = "spdif_ao_out";
 						function = "spdif_ao_out";
-						drive-strength-microamp = <500>;
+						drive-strength-microamp = <3000>;
 						bias-disable;
 					};
 				};
-- 
2.43.0


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Re: [PATCH] arm64: dts: amlogic: g12: bump spdif output drive strength

[Neil Armstrong]

Hi,

On Tue, 25 Jun 2024 13:54:41 +0200, Jerome Brunet wrote:
> Spdif output currently uses a 0.5mA drive strength by default.
> While the result depends on how the spdif output is hooked to
> rest of the system, this is a bit weak and signal quality
> may be poor. This was reported on the vim3l for example.
> 
> Increase the drive strength to 3mA, as used for TDM, to be on the
> safe side.
> 
> [...]

Thanks, Applied to https://git.kernel.org/pub/scm/linux/kernel/git/amlogic/linux.git (v6.11/arm64-dt)

[1/1] arm64: dts: amlogic: g12: bump spdif output drive strength
      https://git.kernel.org/amlogic/c/84f6ab5fedf735a447080e2fd286eff9859cd199

These changes has been applied on the intermediate git tree [1].

The v6.11/arm64-dt branch will then be sent via a formal Pull Request to the Linux SoC maintainers
for inclusion in their intermediate git branches in order to be sent to Linus during
the next merge window, or sooner if it's a set of fixes.

In the cases of fixes, those will be merged in the current release candidate
kernel and as soon they appear on the Linux master branch they will be
backported to the previous Stable and Long-Stable kernels [2].

The intermediate git branches are merged daily in the linux-next tree [3],
people are encouraged testing these pre-release kernels and report issues on the
relevant mailing-lists.

If problems are discovered on those changes, please submit a signed-off-by revert
patch followed by a corrective changeset.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/amlogic/linux.git
[2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
[3] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

-- 
Neil


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