Re: [PATCH V4] i2c: qcom-geni: Add dynamic transfer timeout based on transfer length and frequency
Konrad Dybcio <[email protected]>
| Newsgroups | org.kernel.vger.linux-i2c,org.freedesktop.lists.dri-devel,org.kernel.vger.linux-arm-msm,org.kernel.vger.linux-kernel,org.kernel.vger.linux-media |
|---|---|
| Message-ID | <[email protected]> |
On 7/15/26 6:06 AM, Mukesh Savaliya wrote: > Hi Aniket, Thanks for addressing previous comments. > > On 7/10/2026 9:40 PM, Aniket Randive wrote: >> The driver uses a static XFER_TIMEOUT of HZ (1 second) for all transfers >> regardless of message length or bus frequency, causing unnecessary >> delays on error paths. >> >> Compute the timeout dynamically from message length and bus frequency >> with a 10x safety margin over the theoretical wire time. Add a 300ms >> floor to budget for I2C clock stretching, where a slave may hold SCL >> low indefinitely during internal processing. This detects real hangs > not only internal processing but it may go bad holding SCL low indefinitely. >> 3x faster than the old 1s static timeout. > Meaning, in such case/scenario, don't need to wait till fixes timeout. > I guess, 3x faster is relative to the 1 sec, but for larger data and slower frequency it may not be 3x. Hence, correct it accordingly. >> >> For GPI multi-descriptor transfers, use the maximum message length across >> all queued messages as the per-completion timeout. >> >> Signed-off-by: Aniket Randive <[email protected]> >> --- [...] >> +/* 300ms floor: budget for clock stretching; slave may hold SCL low indefinitely */ > Already explained in commit log, can remove second part. This is very much non-obvious, please keep it Konrad