Revision 29664923725a384dc7e0f74af7c66e5ab7bb2a26 authored by Marco Giunta on 18 October 2021, 16:25:52 UTC, committed by Takashi Iwai on 19 October 2021, 06:07:01 UTC
When a Jieli Technology USB Webcam is connected, the video part works well, but the mic sound is speeded up. On dmesg there are messages about different rates from the runtime rates, warnings about volume resolution and lastly, the log is filled, every 5 seconds, with retire_capture_urb error messages. The mic works only when ep packet size is set to wMaxPacketSize (normal sound and no more retire_capture_urb error messages). Skipping reading sample rate, fixes the messages about different rates and forcing a volume resolution, fixes warnings about volume range. I have arbitrarily choosed the value (16): I read in a comment that there should be no more than 255 levels, so 4096 (max volume) / 16 = 0-255. Signed-off-by: Marco Giunta <giun7a@gmail.com> Link: https://lore.kernel.org/r/20211018162552.12082-1-giun7a@gmail.com Signed-off-by: Takashi Iwai <tiwai@suse.de>
1 parent eadeb06
crc64.c
// SPDX-License-Identifier: GPL-2.0
/*
* Normal 64-bit CRC calculation.
*
* This is a basic crc64 implementation following ECMA-182 specification,
* which can be found from,
* https://www.ecma-international.org/publications/standards/Ecma-182.htm
*
* Dr. Ross N. Williams has a great document to introduce the idea of CRC
* algorithm, here the CRC64 code is also inspired by the table-driven
* algorithm and detail example from this paper. This paper can be found
* from,
* http://www.ross.net/crc/download/crc_v3.txt
*
* crc64table[256] is the lookup table of a table-driven 64-bit CRC
* calculation, which is generated by gen_crc64table.c in kernel build
* time. The polynomial of crc64 arithmetic is from ECMA-182 specification
* as well, which is defined as,
*
* x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
* x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
* x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
* x^7 + x^4 + x + 1
*
* Copyright 2018 SUSE Linux.
* Author: Coly Li <colyli@suse.de>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/crc64.h>
#include "crc64table.h"
MODULE_DESCRIPTION("CRC64 calculations");
MODULE_LICENSE("GPL v2");
/**
* crc64_be - Calculate bitwise big-endian ECMA-182 CRC64
* @crc: seed value for computation. 0 or (u64)~0 for a new CRC calculation,
* or the previous crc64 value if computing incrementally.
* @p: pointer to buffer over which CRC64 is run
* @len: length of buffer @p
*/
u64 __pure crc64_be(u64 crc, const void *p, size_t len)
{
size_t i, t;
const unsigned char *_p = p;
for (i = 0; i < len; i++) {
t = ((crc >> 56) ^ (*_p++)) & 0xFF;
crc = crc64table[t] ^ (crc << 8);
}
return crc;
}
EXPORT_SYMBOL_GPL(crc64_be);
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