Messages in this thread | | | From | Ben Whitten <> | Date | Wed, 14 Aug 2019 14:09:11 +0100 | Subject | Re: [PATCH] regmap: fix writes to non incrementing registers |
| |
On Wed, 14 Aug 2019 at 11:01, Mark Brown <broonie@kernel.org> wrote: > > On Tue, Aug 13, 2019 at 10:22:51PM +0100, Ben Whitten wrote: > > > @@ -1489,10 +1489,11 @@ static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg, > > WARN_ON(!map->bus); > > > > /* Check for unwritable registers before we start */ > > - for (i = 0; i < val_len / map->format.val_bytes; i++) > > - if (!regmap_writeable(map, > > - reg + regmap_get_offset(map, i))) > > - return -EINVAL; > > + if (!regmap_writeable_noinc(map, reg)) > > + for (i = 0; i < val_len / map->format.val_bytes; i++) > > + if (!regmap_writeable(map, > > + reg + regmap_get_offset(map, i))) > > + return -EINVAL; > > This feels like we're getting ourselves confused about nonincrementing > registers and probably have other breakage somewhere else - we're > already checking for nonincrementability in regmap_write_noinc(), and > here we're only checking if the first register in the block has that > property which might blow up on us if there's a register in the middle > of the block that is nonincrementable. If we're going to check this > here I think we should check on every register, but this is > _raw_write_impl() which is part of the call path for implementing > regmap_noinc_write() so checking here will break the API purpose > designed for nonincrementing writes.
So it appeared that the last patch in this area for validating a register block [1] broke the regmap_noinc_write use case. Because regmap_noinc_write calls _regmap_raw_write and in turn hits the _regmap_raw_write_impl, the val_len is the depth of the one register to write to and not a block of registers which is assumed by the previous check. By inserting a check that the first (and only) register is a noinc one allows me to start writing to my FIFO again.
I'm all for an alternative solution though if there is a cleaner approach.
Kind regards, Ben
[1] https://lore.kernel.org/patchwork/patch/1057184/
| |