Hi Greg,
On Tue, Mar 07, 2023 at 05:53:02PM +0100, Greg Kroah-Hartman wrote:
> From: Daniel Golle <daniel@xxxxxxxxxxxxxx>
>
> [ Upstream commit 697c3892d825fb78f42ec8e53bed065dd728db3e ]
>
> reg_base and reg_downshift currently don't have any effect if used with
> a regmap_bus or regmap_config which only offers single register
> operations (ie. reg_read, reg_write and optionally reg_update_bits).
>
> Fix that and take them into account also for regmap_bus with only
> reg_read and read_write operations by applying reg_base and
> reg_downshift in _regmap_bus_reg_write, _regmap_bus_reg_read.
>
> Also apply reg_base and reg_downshift in _regmap_update_bits, but only
> in case the operation is carried out with a reg_update_bits call
> defined in either regmap_bus or regmap_config.
I was waiting for this one to be back-ported. Anyone else can disagree
with me, but I'm on the fence as to whether it should go back to
stable branches.
The only user of reg_base and reg_downshift in 6.1 / 6.2 is
drivers/mfd/ocelot-spi.c, and these don't use reg_read() or reg_write()
so are unaffected by this fix.
On one hand, it isn't fixing any existing 'bugs'. On the other hand,
the documentation I wrote was confusing / misleading, and people
developing against the stable kernels might get behavior that they
didn't expect. Daniel had the misfortune of experiencing this.
Again, I'm on the fence - I just want to make sure the scope is
understood.
Thanks!
>
> Fixes: 0074f3f2b1e43d ("regmap: allow a defined reg_base to be added to every address")
> Fixes: 86fc59ef818beb ("regmap: add configurable downshift for addresses")
> Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
> Tested-by: Colin Foster <colin.foster@xxxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/Y9clyVS3tQEHlUhA@xxxxxxxxxxxxxx
> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> drivers/base/regmap/regmap.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
> index d12d669157f24..d2a54eb0efd9b 100644
> --- a/drivers/base/regmap/regmap.c
> +++ b/drivers/base/regmap/regmap.c
> @@ -1942,6 +1942,8 @@ static int _regmap_bus_reg_write(void *context, unsigned int reg,
> {
> struct regmap *map = context;
>
> + reg += map->reg_base;
> + reg >>= map->format.reg_downshift;
> return map->bus->reg_write(map->bus_context, reg, val);
> }
>
> @@ -2840,6 +2842,8 @@ static int _regmap_bus_reg_read(void *context, unsigned int reg,
> {
> struct regmap *map = context;
>
> + reg += map->reg_base;
> + reg >>= map->format.reg_downshift;
> return map->bus->reg_read(map->bus_context, reg, val);
> }
>
> @@ -3231,6 +3235,8 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
> *change = false;
>
> if (regmap_volatile(map, reg) && map->reg_update_bits) {
> + reg += map->reg_base;
> + reg >>= map->format.reg_downshift;
> ret = map->reg_update_bits(map->bus_context, reg, mask, val);
> if (ret == 0 && change)
> *change = true;
> --
> 2.39.2
>
>
>
