Hans Verkuil <hverk...@xs4all.nl> writes:
>> +/*
>> + *
>> + * The device delivers data in chunks of 0x400 bytes.
>> + * The four first bytes is a magic header to identify the chunks.
>> + * 0xaa 0xaa 0x00 0x00 = saa7113 Active Video Data
>> + * 0xaa 0xaa 0x00 0x01 = PCM - 24Bit 2 Channel audio data
>> + */
>> +static void process_packet(struct smi2021_dev *dev, u8 *p, int len)
>> +{
>> + int i;
>> + u32 *header;
>> +
>> + if (len % 0x400 != 0) {
>> + printk_ratelimited(KERN_INFO "smi2021::%s: len: %d\n",
>> + __func__, len);
>> + return;
>> + }
>> +
>> + for (i = 0; i < len; i += 0x400) {
>> + header = (u32 *)(p + i);
>> + switch (__cpu_to_be32(*header)) {
>
> That's not right. You probably mean __be32_to_cpu, that makes more sense.
>
>> + case 0xaaaa0000: {
>> + parse_video(dev, p+i+4, 0x400-4);
>> + break;
>> + }
>> + case 0xaaaa0001: {
>> + smi2021_audio(dev, p+i+4, 0x400-4);
>> + break;
>> + }
This could be just me, but I would have done it like this to take
advantage of compile time constant conversions (and also dropping the
noisy extra {}s):
switch (*header) {
case cpu_to_be32(0xaaaa0000):
parse_video(dev, p+i+4, 0x400-4);
break;
case cpu_to_be32(0xaaaa0001):
smi2021_audio(dev, p+i+4, 0x400-4);
break;
..
>From the name of the function I assume the difference may actually be
measurable here if this runs for every processed packet.
Bjørn
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