On Mon, Oct 21, 2019 at 06:41:05PM +0300, Andi Shyti wrote: > Hi Stephan, > > > Not sure if you saw my comment regarding your patch [1], > > so I'll just repeat it properly inline here: > > > > [1]: https://patchwork.kernel.org/patch/11178515/#22927311 > > > > On Sun, Oct 20, 2019 at 11:28:55PM +0300, Andi Shyti wrote: > > > The exchange of data to and from the mms114 touchscreen never > > > exceeds 256 bytes. In the worst case it goes up to 80 bytes in > > > the interrupt handler while reading the events. > > > > > > > i2c_smbus_read_i2c_block_data() is actually limited to > > I2C_SMBUS_BLOCK_MAX = 32. > > oh sorry, I don't know how I slipped on this. > > But this means that the i2c in the kernel is wrong (or outdated), > smbus specifies 256 bytes of data[*]. I might have relied on the > specification more than the code. > > I guess SMBUS needs some update. You are right. It seems like that part of the specification was changed with SMBus version 3.0 [1]: D.6 255 Bytes in Process Call: The maximum number of bytes allowed in the Block Write-Block Read Process Call (Section 6.5.8) was increased from 32 to 255. [1]: http://www.smbus.org/specs/SMBus_3_0_20141220.pdf
