On Fri, Jun 16, 2023 at 06:15:35PM +0200, Miquel Raynal wrote: > broonie@xxxxxxxxxx wrote on Fri, 16 Jun 2023 15:20:27 +0100: > > On Fri, Jun 16, 2023 at 04:12:25PM +0200, Miquel Raynal wrote: > > > -#define SPI_DMA_TIMEOUT (msecs_to_jiffies(1000)) > > > +#define SPI_DMA_MIN_TIMEOUT (msecs_to_jiffies(1000)) > > > +#define SPI_DMA_TIMEOUT_PER_10K (msecs_to_jiffies(4)) > > Given that we know the bus speed can't we just calculate this like other > > drivers do (we should probably add a helper TBH)? > I agree we should probably have some kind of easy-to-use helper to > derive a decent timeout value. How do sound the heuristics > proposed here to you ? That would be: > timeout = 1s + 4ms/10k Like I say we should know the transfer speed so we can do better than 4ms/10k - we know how long it takes to clock out each byte, we can just multiply that by the size of the transfer then add some fudge factor for setup/teardown overhead. 1s feels pretty generous too. The sun6i driver for example does max(tfr->len * 8 * 2 / (tfr->speed_hz / 1000), 100U) and just doubles the length based timeout with a minimum of 100ms which seems reasonable.
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