Re: [PATCH v10] ASoC: tas2781: Add tas2781 driver

[Christophe JAILLET]

Le 31/03/2023 à 04:19, Ding, Shenghao a écrit :
> Hi Amadeusz Sławiński
> Thanks for your comment.
> Answer inline.
>
> -----Original Message-----
> From: Amadeusz Sławiński <amadeuszx.slawinski@xxxxxxxxxxxxxxx>
> Sent: Thursday, March 30, 2023 7:54 PM
> To: Shenghao Ding <13916275206@xxxxxxx>; broonie@xxxxxxxxxx; lgirdwood@xxxxxxxxx; perex@xxxxxxxx; pierre-louis.bossart@xxxxxxxxxxxxxxx
> Cc: Lu, Kevin <kevin-lu@xxxxxx>; Ding, Shenghao <shenghao-ding@xxxxxx>; alsa-devel@xxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Xu, Baojun <x1077012@xxxxxx>; Gupta, Peeyush <peeyush@xxxxxx>; Navada Kanyana, Mukund <navada@xxxxxx>
> Subject: [EXTERNAL] Re: [PATCH v10] ASoC: tas2781: Add tas2781 driver
>
> On 3/29/2023 12:01 PM, Shenghao Ding wrote:
> > Create tas2781 driver.
> >
> > Signed-off-by: Shenghao Ding <13916275206@xxxxxxx>
> >
> > ---
> > Changes in v10:
> >    - using be16_to_cpu and be32_to_cpu instead of SMS_HTONS and SMS_HTONL
> >    - optimize and reduce the boundary checks
> >    - Add comments on some kmemdup instead of kzalloc+memcpy
> >    Changes to be committed:
> > 	modified:   sound/soc/codecs/Kconfig
> > 	modified:   sound/soc/codecs/Makefile
> > 	new file:   sound/soc/codecs/tas2781-dsp.c
> > 	new file:   sound/soc/codecs/tas2781-dsp.h
> > 	new file:   sound/soc/codecs/tas2781-i2c.c
> > 	new file:   sound/soc/codecs/tas2781.h
> > ---
>
> ...
>
> > +
> > +static int fw_parse_block_data_kernel(struct tasdevice_fw *tas_fmw,
> > +	struct tasdev_blk *block, const struct firmware *fmw, int offset) {
> > +	const unsigned char *data = fmw->data;
> > +
> > +	if (offset + 16 > fmw->size) {
> > +		dev_err(tas_fmw->dev, "%s: File Size error\n", __func__);
> > +		offset = -EINVAL;
> > +		goto out;
> > +	}
> > +	block->type = be32_to_cpup((__be32 *)&data[offset]);
>
> Wouldn't just be32_to_cpu(data[offset]) work instead of be32_to_cpup?
> Same in other cases.
> [DING] data[] is a char array, the code will convert data[offset], data[offset + 1],
> data[offset + 2] and data[offset + 3] into host instead of data[offset] only.

Not sure to follow you.
Isn't it the purpose of be32_to_cpu() to take a 32 bits word, in other 
words 4 x 8 bits char, and swap what if needed (little endian arch)?

It ends to __swab32() ([1] for the "constant" implementation)


be32_to_cpup(&p) ends to __swab32(*p), which really looks to the same as 
be32_to_cpu(p).

Can you elaborate more?

CJ


[1]: 
https://elixir.bootlin.com/linux/v6.3-rc3/source/include/uapi/linux/swab.h#L18