rocknix-joypad: ratelimit the saradc read-failure message - #3250
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joypad_adc_check() runs from the input polling loop. When joypad_adc_read() fails it returns 0, and the driver logs at dev_err level with no ratelimiting - so a persistent ADC failure emits one line per poll, about 8 per second, for as long as the condition lasts. On a 1.5Mbaud serial console that is a permanent stream of identical lines. It drowns out whatever actually broke, and it adds console work to a machine that by that point is usually already in trouble. Observed on a Gusgu H7 (RK3326) whenever the SARADC stops answering: tens of thousands of identical messages, which actively hindered debugging an unrelated interrupt storm. Use dev_err_ratelimited() at all three call sites. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01985tp15STZZvPFMfnVBGnm
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Summary
joypad_adc_check()runs from the input polling loop. Whenjoypad_adc_read()fails it returns 0 and the driver logs atdev_errlevel with no ratelimiting, so a persistent ADC failure emits one line per poll — about 8 per second — for as long as the condition lasts.On a 1.5Mbaud serial console that is a permanent stream of identical lines. It drowns out whatever actually broke, and it adds console work to a machine that by that point is usually already in trouble.
Switches the three call sites to
dev_err_ratelimited(). A genuine ADC failure still gets reported; it just stops repeating thousands of times.Testing
saradc channels[N]!messages — this actively hindered debugging an unrelated interrupt storm, since the useful output scrolled away. After, the message appears at the ratelimited rate and the surrounding log stays readable.Additional Context
continueon failure is untouched.dev_err_ratelimited()is the standard helper for exactly this case and is already used widely in the kernel's input drivers.rocknix-joypad, which is shared across device families, so it is worth a glance from someone with other hardware — but the change is confined to three log statements.AI Usage
Did you use AI tools to help write this code? YES — Claude Code was used to trace the log flood back to the polling loop and to draft the patch and this description.