Re: [PATCH v2] regmap-i2c: Subtract reg size from max_write

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, May 23, 2024 at 04:14:36PM -0500, Jim Wylder wrote:
> Currently, when an adapter defines a max_write_len quirk,
> the data will be chunked into data sizes equal to the
> max_write_len quirk value.  But the payload will be increased by
> the size of the register address before transmission.  The
> resulting value always ends up larger than the limit set
> by the quirk.
> 
> Avoid this error by setting regmap's max_write to the quirk's
> max_write_len minus the number of bytes for the register and
> padding.  This allows the chunking to work correctly for this
> limited case without impacting other use-cases.
> 
> Signed-off-by: Jim Wylder <jwylder@google.com>
> ---
>  drivers/base/regmap/regmap-i2c.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
> index 3ec611dc0c09..a905e955bbfc 100644
> --- a/drivers/base/regmap/regmap-i2c.c
> +++ b/drivers/base/regmap/regmap-i2c.c
> @@ -350,7 +350,8 @@ static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
>  
>  		if (quirks->max_write_len &&
>  		    (bus->max_raw_write == 0 || bus->max_raw_write > quirks->max_write_len))
> -			max_write = quirks->max_write_len;
> +			max_write = quirks->max_write_len -
> +				(config->reg_bits + config->pad_bits) / BITS_PER_BYTE;
>  
>  		if (max_read || max_write) {
>  			ret_bus = kmemdup(bus, sizeof(*bus), GFP_KERNEL);
> -- 
> 2.45.1.288.g0e0cd299f1-goog
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
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  Please read the section entitled "The canonical patch format" in the
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  needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about
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thanks,

greg k-h's patch email bot