The microphones (2x) on Surface Pro 11 are currently ususable due to a
misconfigured sample rate, which results in a very distorted recording
with the voice barely audible.

Under Windows, the DMIC0_CTL register is set to 0x00000005 while
recording:

   bit 0 = 1 --> DMIC0 enabled
bits 3:1 = 2 --> DMIC clock divider = /4

The current dmic-sample-rate of 4800000 corresponds to the default DMIC
clock divider of /2.

Dropping dmic-sample-rate to 2400000 sets the divider to /4, matching
the working Windows configuration and resulting in perfect audio.

While we're at it, remove the reference to dmic23_default, as we only
have two microphones and don't need to configure the pins for a 3rd/4th
microphone.

Signed-off-by: Dale Whinham <daleyo@gmail.com>
---
 arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi b/arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi
index 7559557610ed..28ca2fe678ef 100644
--- a/arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi
+++ b/arch/arm64/boot/dts/qcom/x1-microsoft-denali.dtsi
@@ -863,11 +863,11 @@ spkr_01_sd_n_active: spkr-01-sd-n-active-state {
 };
 
 &lpass_vamacro {
-	pinctrl-0 = <&dmic01_default>, <&dmic23_default>;
+	pinctrl-0 = <&dmic01_default>;
 	pinctrl-names = "default";
 
 	vdd-micb-supply = <&vreg_l1b_1p8>;
-	qcom,dmic-sample-rate = <4800000>;
+	qcom,dmic-sample-rate = <2400000>;
 };
 
 &mdss {

---
base-commit: 8d3ae59288f1e7d58d76558a6ee96d533bc5019f
change-id: 20260830-surface-pro-11-mic-fix-4b5878500266

Best regards,
--  
Dale Whinham <daleyo@gmail.com>

On Sun, 30 Aug 2026 18:40:07 +0100, Dale Whinham wrote:
> The microphones (2x) on Surface Pro 11 are currently ususable due to a
> misconfigured sample rate, which results in a very distorted recording
> with the voice barely audible.
> 
> Under Windows, the DMIC0_CTL register is set to 0x00000005 while
> recording:
> 
> [...]

Applied, thanks!

[1/1] arm64: dts: qcom: x1-denali: Fix microphone distortion
      commit: 35ce3c571297aee13c6da604d022929fd1aa9efb

Best regards,
-- 
Bjorn Andersson <andersson@kernel.org>

On 26-08-30 18:40:07, Dale Whinham wrote:
> The microphones (2x) on Surface Pro 11 are currently ususable due to a
> misconfigured sample rate, which results in a very distorted recording
> with the voice barely audible.
> 
> Under Windows, the DMIC0_CTL register is set to 0x00000005 while
> recording:
> 
>    bit 0 = 1 --> DMIC0 enabled
> bits 3:1 = 2 --> DMIC clock divider = /4
> 
> The current dmic-sample-rate of 4800000 corresponds to the default DMIC
> clock divider of /2.
> 
> Dropping dmic-sample-rate to 2400000 sets the divider to /4, matching
> the working Windows configuration and resulting in perfect audio.
> 
> While we're at it, remove the reference to dmic23_default, as we only
> have two microphones and don't need to configure the pins for a 3rd/4th
> microphone.
> 
> Signed-off-by: Dale Whinham <daleyo@gmail.com>

Reviewed-by: Abel Vesa <abel.vesa@oss.qualcomm.com>

On 8/30/26 7:40 PM, Dale Whinham wrote:
> The microphones (2x) on Surface Pro 11 are currently ususable due to a
> misconfigured sample rate, which results in a very distorted recording
> with the voice barely audible.
> 
> Under Windows, the DMIC0_CTL register is set to 0x00000005 while
> recording:
> 
>    bit 0 = 1 --> DMIC0 enabled
> bits 3:1 = 2 --> DMIC clock divider = /4
> 
> The current dmic-sample-rate of 4800000 corresponds to the default DMIC
> clock divider of /2.
> 
> Dropping dmic-sample-rate to 2400000 sets the divider to /4, matching
> the working Windows configuration and resulting in perfect audio.
> 
> While we're at it, remove the reference to dmic23_default, as we only
> have two microphones and don't need to configure the pins for a 3rd/4th
> microphone.
> 
> Signed-off-by: Dale Whinham <daleyo@gmail.com>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad