ARM: dts: tegra30-microsoft-surface-rt: Fix WM8962 SPKVDD supply - #140
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ARM: dts: tegra30-microsoft-surface-rt: Fix WM8962 SPKVDD supply#140blakegordon wants to merge 1 commit into
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The WM8962 Class-D speaker outputs require SPKVDD in the 2.5V-5.5V range. The device tree currently wires SPKVDD1/2 to vdd_1v8_sys (1.8V), below the minimum. On postmarketOS/grate the codec probes and playback succeeds in software, but no sound is produced and dmesg reports ASoC error (-16) at register 0x30 and DC servo timeouts. Use vdd_5v0_sys for SPKVDD1/2; digital/analog core supplies stay at 1.8V. Signed-off-by: Blake Gordon <blakegordon@berkeley.edu>
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Technically, the change is correct, SPKVDD should be 5v. But in practice both 5v and 1.8v regulators are defined as always-on in device-tree and driver doesn't care about actual voltages, hence the change shall have no practical effect and shouldn't fix anything. |
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Thanks for the feedback. We can close the P/R since testing reveals no improvement in getting sound from the device. (P.S. Any suggestions on that? It's unclear to me whether sound is working for other people running postmarket on Surface RT....) |
Member
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You may try to find from where that error originates in the code |
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Summary
Fix silent audio on Microsoft Surface RT by wiring the WM8962 Class-D speaker
amplifier supplies (SPKVDD1/2) to the board 5 V rail instead of 1.8 V.
Problem
On postmarketOS with
linux-postmarketos-grate, the WM8962 codec probessuccessfully and ALSA playback appears to work, but no sound is produced from
the internal speakers or headphones. During playback, mixer routes and Class-D
enable bits look correct in software.
dmesgreports on every playback attempt:Root cause
Per the WM8962 datasheet, SPKVDD must be in the 2.5 V–5.5 V range for the
Class-D speaker outputs (SPKOUTL/R). The device tree currently assigns both
SPKVDD1-supplyandSPKVDD2-supplytovdd_1v8_sys(1.8 V), which is belowthe minimum operating voltage for the speaker amplifier.
Digital and analog core supplies correctly remain on 1.8 V; only the speaker
amplifier rails need the higher voltage.
Fix
Point
SPKVDD1-supplyandSPKVDD2-supplyatvdd_5v0_sys, which is alreadymodeled in the device tree and used by other board peripherals (backlight, USB
VBUS, etc.).
The EFI variant (
tegra30-microsoft-surface-rt-efi.dts) includes this file, sono separate change is required there.
Testing
speaker-test -Dhw:1,0dmesgno longer reports WM8962 register0x30errors / DC servo timeouts during playbackTested-by: Blake Gordon blakegordon@berkeley.edu (pending kernel rebuild)
References
linux-postmarketos-grate-7.0.1-r0