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commit f6fb1f9 ("sdcard: Correct CRC16 offset in sd_function_switch()") changed the 16-bit CRC to be stored at offset 64. In fact, this CRC calculation is completely wrong. From the original codes, it wants to calculate the CRC16 of the first 64 bytes of sd->data[], however passing 64 as the `width` to sd_crc16() actually counts 256 bytes starting from the `message` for the CRC16 calculation, which is not what we want. Besides that, it seems existing sd_crc16() algorithm does not match the SD spec, which says CRC16 is the CCITT one but the calculation does not produce expected result. It turns out the CRC16 was never transferred outside the sd core, as in sd_read_byte() we see: if (sd->data_offset >= 64) sd->state = sd_transfer_state; Given above reasons, let's drop it. Signed-off-by: Bin Meng <bin.meng@windriver.com> Tested-by: Pragnesh Patel <pragnesh.patel@sifive.com> Reviewed-by: Pragnesh Patel <pragnesh.patel@sifive.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Message-Id: <20210123104016.17485-6-bmeng.cn@gmail.com> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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