# Re: \[PATCH 2/2\] nvmem: iomap: new driver exposing NVMEM accessible using I/O mapping

- From: Rafał Miłecki \<rafal@milecki.pl\>
- Date: 2021-03-05 10:59:32 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2021/03/6289443
- Thread: https://ratatoskr.run/linux-devicetree/2021/03/6288379/t.md

```text
On 05.03.2021 11:33, Srinivas Kandagatla wrote:
> On 05/03/2021 10:24, Rafał Miłecki wrote:
>>>>
>>>> +static int iomap_read(void *context, unsigned int offset, void *val,
>>>> +              size_t bytes)
>>>> +{
>>>> +    struct iomap *priv = context;
>>>> +    u8 *src = priv->base + offset;
>>>> +    u8 *dst = val;
>>>> +    size_t tmp;
>>>> +
>>>> +    tmp = offset % 4;
>>>> +    memcpy_fromio(dst, src, tmp);
>>>> +    dst += tmp;
>>>> +    src += tmp;
>>>> +    bytes -= tmp;
>>>> +
>>>> +    tmp = rounddown(bytes, 4);
>>>> +    __ioread32_copy(dst, src, tmp / 4);
>>>> +    dst += tmp;
>>>> +    src += tmp;
>>>> +    bytes -= tmp;
>>>> +
>>>> +    memcpy_fromio(dst, src, bytes);
>>>> +
>>>
>>>
>>> You could just do this!
>>>
>>>      while (bytes--)
>>>          *val++ = readb(priv->base + offset + i++);
>>
>> Do you mean that as replacement for "memcpy_fromio" or the whole
>> function code?
>
> Yes please!
>
>> The reason for using __ioread32_copy() was to improve reading
>> performance (using aligned 32 bit access where possible). I'm not sure
>> if that really matters?
>
> Just simple while loop is much readable than the previous code TBH!
>
>>
>
>> P.S.
>> Please don't yell at me in every sentence :( Makes me a bit sad :(
> Sorry!! I did not mean anything as such! :-)

All clear (I hope)! Thanks for your review!

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```