From: Jose Abreu [mailto:jose.abreu@xxxxxxxxxxxx] > On 29-11-2018 12:47, David Laight wrote: > > From: Jose Abreu > >> Sent: 29 November 2018 12:42 > >> > >> Some ARC CPU's do not support unaligned loads/stores. Currently, generic > >> implementation of reads{b/w/l}()/writes{b/w/l}() is being used with ARC. > >> This can lead to misfunction of some drivers as generic functions do a > >> plain dereference of a pointer that can be unaligned. > >> > >> Let's use {get/put}_unaligned() helper instead of plain dereference of > >> pointer in order to fix this. > > Is it worth adding a check for the pointer being aligned? > > We could but then we would need to know which CPU version is > currently running because some ARC processors support unaligned > accesses. Eh? If the CPU supports unaligned accesses you could patch the code to do unaligned accesses. I was thinking of the (probably likely) case where the pointer is actually aligned. An extra check for ((pointer) & 3) is almost certainly a 'win' over the byte accesses and shift/mask/or use by get/put_unaligned(). The IO accesses probably dominate making more complex optimisations less likely to have any benefit. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-snps-arc mailing list linux-snps-arc@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-snps-arc
