[PATCH] regmap: mmio: Allow passing an empty config->reg_stride

[PATCH] regmap: mmio: Allow passing an empty config->reg_stride

[Maxime Chevallier]

Regmap's stride is used for MMIO regmaps to check the correctness of
reg_width. However, it's acceptable to pass an empty config->reg_stride,
in that case the actual stride used is 1.

There are valid cases now to pass an empty stride, when using
down/upshifting of register address. In this case, the stride value
loses its sense, so ignore the reg_width when the stride isn't set.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
This patch is a followup on the discussion here [1]. The regmap core
actually supports pretty-well not passing a stride, and uses a value of
1 by default. However regmap-mmio has specific checks for that case,
which is the only place such a check needs to be added.

[1] : https://lore.kernel.org/all/20230420150617.381922-1-maxime.chevallier@bootlin.com/

 drivers/base/regmap/regmap-mmio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
index 3ccdd86a97e7..8132b5c101c4 100644
--- a/drivers/base/regmap/regmap-mmio.c
+++ b/drivers/base/regmap/regmap-mmio.c
@@ -448,7 +448,7 @@ static struct regmap_mmio_context *regmap_mmio_gen_context(struct device *dev,
 	if (min_stride < 0)
 		return ERR_PTR(min_stride);
 
-	if (config->reg_stride < min_stride)
+	if (config->reg_stride && config->reg_stride < min_stride)
 		return ERR_PTR(-EINVAL);
 
 	if (config->use_relaxed_mmio && config->io_port)
-- 
2.40.1

Re: [PATCH] regmap: mmio: Allow passing an empty config->reg_stride

[Mark Brown]

On Thu, 11 May 2023 16:27:35 +0200, Maxime Chevallier wrote:
> Regmap's stride is used for MMIO regmaps to check the correctness of
> reg_width. However, it's acceptable to pass an empty config->reg_stride,
> in that case the actual stride used is 1.
> 
> There are valid cases now to pass an empty stride, when using
> down/upshifting of register address. In this case, the stride value
> loses its sense, so ignore the reg_width when the stride isn't set.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git for-next

Thanks!

[1/1] regmap: mmio: Allow passing an empty config->reg_stride
      commit: e12ff28764937dd58c8613f16065da60da149048

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark