On Tue, Jun 20, 2017 at 10:28:35AM +0200, Uwe Kleine-König wrote: > Cc += Andy Duan > > On Tue, Jun 20, 2017 at 10:20:42AM +0200, Michail Georgios Etairidis wrote: > > > > The i2c-imx driver incorrectly uses readb()/writeb() to read and > > write to the appropriate registers when performing a repeated start. > > The appropriate imx_i2c_read_reg()/imx_i2c_write_reg() functions > > should be used instead. Performing a repeated start results in > > a kernel panic. The platform is imx. > > I really wonder why this didn't pop up earlier, maybe repeated start > just isn't that usual. Quite the contrary, read a register or something from an EEPROM and you should have the write (for the memory pointer) and the read (actual data) connected with a repeated start. The readb() calls are only accessed when a read message is not the last message. Since most transfers look like what I described above, this is not so super often. Add to that that not everyone reports such patches back upstream, this might go unnoticed for a while. So, thanks Michail for the patch and keeping at it! Note: I found there is some code duplication in the driver. Both 'if (is_lastmsg)' blocks look like copied to me...
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