RE: [PATCH 1/3] mfd: Add realtek USB card reader driver

[Roger Tseng]

Hi Dan,

>> +int rtsx_usb_ep0_write_register(struct rtsx_ucr *ucr, u16 addr,
>> +             u8 mask, u8 data)
>> +{
>> +     u16 value = 0, index = 0;
>> +
>> +     value |= (u16)(3 & 0x03) << 14;
>> +     value |= (u16)(addr & 0x3FFF);
>
>Don't do pointless things:
>
>        value |= 0x03 << 14;
>        value |= addr & 0x3FFF;
>
>> +     value = ((value << 8) & 0xFF00) | ((value >> 8) & 0x00FF);
>
>This is an endian conversion?  It is buggy.  Use the kernel endian
>conversion functions cpu_to_le16().

This is not a conversion for endianess with respect to CPU but for command format  of the device. It should always be performed regardless of platform.

In other words, it could be equivalent to:
        value |= 0x03 << 6; // lower byte
        value |= (addr & 0x3F00) >> 8; // lower byte
        value |= (addr & 0xFF) << 8; //higher byte

We think the previous form is easier to read. Should we keep it or change to the later one?--
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