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 <b2ccaf40-fe04-490f-a625-4c502c038627@roeck-us.net>
In-Reply-To: <b2ccaf40-fe04-490f-a625-4c502c038627@roeck-us.net>
From: Joy Chakraborty <joychakr@google.com>
Date: Thu, 6 Jun 2024 14:52:51 +0530
Message-ID: <CAOSNQF3bw4+-SPEVf9wwsrt0L-6VNK0NWuDKW6AhX701+OKjsg@mail.gmail.com>
Subject: Re: [PATCH v1 01/17] hwmon: pmbus: adm1266: Change nvmem
 reg_read/write return type
To: Guenter Roeck <linux@roeck-us.net>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, 
	Lars-Peter Clausen <lars@metafoo.de>, Sakari Ailus <sakari.ailus@linux.intel.com>, 
	Bingbu Cao <bingbu.cao@intel.com>, Zhihao Cheng <chengzhihao1@huawei.com>, 
	Jerome Brunet <jbrunet@baylibre.com>, 
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>, linux-hwmon@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, 
	linux-media@vger.kernel.org, linux-i2c@vger.kernel.org, 
	linux-gpio@vger.kernel.org, linux-mtd@lists.infradead.org, 
	linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 
	linux-amlogic@lists.infradead.org, linux-sunxi@lists.linux.dev, 
	linux-tegra@vger.kernel.org, linux-usb@vger.kernel.org, manugautam@google.com
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On Thu, Jun 6, 2024 at 2:59=E2=80=AFAM Guenter Roeck <linux@roeck-us.net> w=
rote:
>
> On 6/5/24 10:59, Joy Chakraborty wrote:
> > Change nvmem read/write function definition return type to ssize_t.
> >
> > Signed-off-by: Joy Chakraborty <joychakr@google.com>
> > ---
> >   drivers/hwmon/pmbus/adm1266.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm126=
6.c
> > index 2c4d94cc8729..7eaab5a7b04c 100644
> > --- a/drivers/hwmon/pmbus/adm1266.c
> > +++ b/drivers/hwmon/pmbus/adm1266.c
> > @@ -375,7 +375,7 @@ static int adm1266_nvmem_read_blackbox(struct adm12=
66_data *data, u8 *read_buff)
> >       return 0;
> >   }
> >
> > -static int adm1266_nvmem_read(void *priv, unsigned int offset, void *v=
al, size_t bytes)
> > +static ssize_t adm1266_nvmem_read(void *priv, unsigned int offset, voi=
d *val, size_t bytes)
> >   {
> >       struct adm1266_data *data =3D priv;
> >       int ret;
> > @@ -395,7 +395,7 @@ static int adm1266_nvmem_read(void *priv, unsigned =
int offset, void *val, size_t
> >
> >       memcpy(val, data->dev_mem + offset, bytes);
> >
> > -     return 0;
> > +     return bytes;
> >   }
> >
> >   static int adm1266_config_nvmem(struct adm1266_data *data)
>
> The series doesn't explain what a driver is supposed to do if it
> only transfers part of the data but not all of it due to an error,
> or because the request exceeded the size of the media.
>
This patch series is actually a follow up on
https://lore.kernel.org/all/20240206042408.224138-1-joychakr@google.com/
which has now been reverted . I shall try to collate it and send it
again with a better explanation.

> For example, this driver still returns an error code if it successfully
> transferred some data but not all of it, or if more data was requested
> than is available.
>
> I didn't check other drivers, but I would assume that many of them
> have the same or a similar problem.
>
> Guenter
>