On 13:47-20240903, Nishanth Menon wrote:
> syscon has always set the optional max_register configuration of
> regmap to ensure the correct checks are in place. However, a recent
> commit 0ec74ad3c157 ("regmap: rework ->max_register handling")
> introduced explicit configuration in regmap framework for register
> maps that is exactly 1 register, when max_register is pointing to a
> valid register 0. This commit solved a previous limitation of regmap
> framework.
>
> Update syscon driver to consistent in regmap configuration for
> all sizes of syscons by using this new capability by setting
> max_register_is_0, when the max_register is valid and 0.
>
> Signed-off-by: Nishanth Menon <nm@xxxxxx>
> ---
>
> Based on my search
> https://gist.github.com/nmenon/d537096d041fa553565fba7577d2cd24, the
> pattern of syscon registers that may potentially be impacted by this
> patch (that are exactly 1 register wide) is probably limited, though
> this patch in itself was inspired by a buggy driver code fixed in
> https://lore.kernel.org/linux-pm/20240828131915.3198081-1-nm@xxxxxx/
> I have tried to Cc lists that may be interested in looking closer to
> avoid un-intended side-effects.
>
> Changes since V1:
> * Incorporate review comments by rewording commit message and $subject
> and dropped Fixes.
> * No functional change to the patch.
> * Expand the CC list to notify potential users.
>
> V1: https://lore.kernel.org/all/20240828121008.3066002-1-nm@xxxxxx/
>
> Cc: Mark Brown <broonie@xxxxxxxxxx>
> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> Cc: linux-arm-msm@xxxxxxxxxxxxxxx
> Cc: Bjorn Andersson <andersson@xxxxxxxxxx>
> Cc: bcm-kernel-feedback-list@xxxxxxxxxxxx
> Cc: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Cc: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
A gentle ping.
>
> drivers/mfd/syscon.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index 2ce15f60eb10..3e1d699ba934 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -108,6 +108,8 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_res)
> syscon_config.reg_stride = reg_io_width;
> syscon_config.val_bits = reg_io_width * 8;
> syscon_config.max_register = resource_size(&res) - reg_io_width;
> + if (!syscon_config.max_register)
> + syscon_config.max_register_is_0 = true;
>
> regmap = regmap_init_mmio(NULL, base, &syscon_config);
> kfree(syscon_config.name);
> @@ -357,6 +359,9 @@ static int syscon_probe(struct platform_device *pdev)
> return -ENOMEM;
>
> syscon_config.max_register = resource_size(res) - 4;
> + if (!syscon_config.max_register)
> + syscon_config.max_register_is_0 = true;
> +
> if (pdata)
> syscon_config.name = pdata->label;
> syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
>
> --
> 2.46.0
>
>
--
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3 1A34 DDB5 849D 1736 249D
