On 4/5/2023 1:21 PM, Ding, Shenghao wrote:
Hi Both
I wrote a test code to verify the be32_to_cpu & be32_to_cpup,
static int __init lkm_init(void)
{
char test_buf[]={0x12, 0x34, 0xab, 0xbc, 0x56, 0x78, 0xef};
unsigned int *k, p, q;
int i;
printk("Hello, Shanghai!\n");
for (i = 0; i < 4; i ++) {
k = (unsigned int *)&test_buf[i];
p = be32_to_cpup((__be32 *)k);
q = be32_to_cpu(test_buf[i]);
printk("%d: *k = 0x%08x p = 0x%08x q = 0x%08x %ld\n",
i, *k, p, q, sizeof(unsigned int));
}
return 0;
}
The output is:
[ 9109.722548] Hello, Shanghai!
[ 9109.726287] 0: *k = 0xbcab3412 p = 0x1234abbc q = 0x12000000 4
[ 9109.727665] 1: *k = 0x56bcab34 p = 0x34abbc56 q = 0x34000000 4
[ 9109.728553] 2: *k = 0x7856bcab p = 0xabbc5678 q = 0xabffffff 4
[ 9109.729308] 3: *k = 0xef7856bc p = 0xbc5678ef q = 0xbcffffff 4
Apparently, be32_to_cpup's output is what I expected.
Looking forward to your comments. Thanks.
It makes sense, as array access reads 8 bit value, you would need to
access value using pointer instead. So instead of doing
be32_to_cpu(test_buf[i]) you would need to do be32_to_cpu(*(test_buf +
i)) if I didn't mess the pointer magic ;)
And then I'm not sure which is better, be32_to_cpup or be32_to_cpu.
BR
Shenghao Ding
-----Original Message-----
From: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Sent: Saturday, April 1, 2023 4:41 AM
To: Ding, Shenghao <shenghao-ding@xxxxxx>; Amadeusz Slawinski <amadeuszx.slawinski@xxxxxxxxxxxxxxx>; Shenghao Ding <13916275206@xxxxxxx>; broonie@xxxxxxxxxx; lgirdwood@xxxxxxxxx; perex@xxxxxxxx; pierre-louis.bossart@xxxxxxxxxxxxxxx
Cc: Lu, Kevin <kevin-lu@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
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
