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SubjectRe: [PATCH v8 03/22] counter: 104-quad-8: Return error when invalid mode during ceiling_write
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On 2/12/21 6:13 AM, William Breathitt Gray wrote:
> The 104-QUAD-8 only has two count modes where a ceiling value makes
> sense: Range Limit and Modulo-N. Outside of these two modes, setting a
> ceiling value is an invalid operation -- so let's report it as such by
> returning -EINVAL.
>
> Fixes: fc069262261c ("counter: 104-quad-8: Add lock guards - generic interface")
> Cc: Syed Nayyar Waris <syednwaris@gmail.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
> drivers/counter/104-quad-8.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index 9691f8612be8..f0608b21196a 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -714,13 +714,14 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
> switch (priv->count_mode[count->id]) {
> case 1:
> case 3:
> + mutex_unlock(&priv->lock);
> quad8_preset_register_set(priv, count->id, ceiling);
> - break;
> + return len;
> }
>
> mutex_unlock(&priv->lock);
>
> - return len;
> + return -EINVAL;
> }
>
> static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,
>

What happens if the register is written to when in the wrong mode?

If it doesn't hurt anything, I would suggest always writing the register
instead so that users don't have to know worry about the fact that the mode
has to be set first.

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