On Mon, 21 Oct 2024, Andy Shevchenko wrote: > On Mon, Oct 21, 2024 at 12:54:16PM +0300, Andy Shevchenko wrote: > > On Mon, Oct 21, 2024 at 12:49:08PM +0300, Ilpo Järvinen wrote: > > > On Mon, 21 Oct 2024, Andy Shevchenko wrote: > > > > On Mon, Oct 21, 2024 at 12:24:57PM +0300, Ilpo Järvinen wrote: > > > > > On Mon, 21 Oct 2024, Andy Shevchenko wrote: > > ... > > > > > > > + for (nc = 0, offset = 0; nc < 4; nc++, offset += 4) > > > > > > + wbuf[nc] = ipc_data_readl(scu, offset); > > > > > > + memcpy(data, wbuf, count); > > > > > > > > > > So do we actually need to read more than > > > > > DIV_ROUND_UP(min(count, 16U), sizeof(u32))? Because that's the approach > > > > > used in intel_scu_ipc_dev_command_with_size() which you referred to. > > > > > > > > I'm not sure I follow. We do IO for whole (16-bytes) buffer, but return only > > > > asked _bytes_ to the user. > > > > > > So always reading 16 bytes is not part of the old workaround? Because it > > > has a "lets read enough" feel. > > > > Ah, now I got it! Yes, we may reduce the reads to just needed ones. > > The idea is that we always have to perform 32-bit reads independently > > on the amount of data we want. > > Oh, looking at the code (*) it seems they are really messed up in the original > with bytes vs. 32-bit words! Since the above has been tested, let me put this > on TODO list to clarify this mess and run with another testing. > > Sounds good to you? Sure, I'm fine with taking the careful approach. > *) the mythical comment about max 5 items for 20-byte buffer is worrying and > now I know why, Those functions with that comment seem to only be called from scu_reg_access() which error checks count > 4. -- i.
