On 2017-10-13 15:29, Alan Cox wrote: > On Thu, 12 Oct 2017 13:35:17 +0200 > Peter Rosin <peda@xxxxxxxxxx> wrote: > >> Hi! >> >> I have encountered an "interesting" bug. It silently corrupts data >> and is generally nasty... >> >> On an I2C bus, driven by the at91 driver and DMA (an Atmel >> sama5d31 chip), I have an 256 byte eeprom (NXP SE97BTP). I'm using >> Linux v4.13. > > If your force the transfer to PIO does it behave ? Does the controller in > fact need to siwtch to PIO for SMBUS ? Like, what if I disable DMA? I saw no way to do that, short of short-cutting a few things in the driver code. So, did that and I cannot tickle the bug. But I don't know if that makes me safe? Ludovic, any reason to believe disabling DMA will prevent these stalls, or will they just appear under different circumstances? I used this dirty "patch" to i2c-at91.c:at91_twi_configure_dma() for testing: - dev->use_dma = true; + //dev->use_dma = true; Cheers, Peter
