hw/ssi: imx_spi: Correct the burst length > 32 bit transfer logic
For the ECSPIx_CONREG register BURST_LENGTH field, the manual says:
0x020 A SPI burst contains the 1 LSB in first word and all 32 bits in second word.
0x021 A SPI burst contains the 2 LSB in first word and all 32 bits in second word.
Current logic uses either s->burst_length or 32, whichever smaller,
to determine how many bits it should read from the tx fifo each time.
For example, for a 48 bit burst length, current logic transfers the
first 32 bit from the first word in the tx fifo, followed by a 16
bit from the second word in the tx fifo, which is wrong. The correct
logic should be: transfer the first 16 bit from the first word in
the tx fifo, followed by a 32 bit from the second word in the tx fifo.
With this change, SPI flash can be successfully probed by U-Boot on
imx6 sabrelite board.
=> sf probe
SF: Detected sst25vf016b with page size 256 Bytes, erase size 4 KiB, total 2 MiB
Fixes: c906a3a015
("i.MX: Add the Freescale SPI Controller")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210129132323.30946-10-bmeng.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@ -185,7 +185,7 @@ static void imx_spi_flush_txfifo(IMXSPIState *s)
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DPRINTF("data tx:0x%08x\n", tx);
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tx_burst = MIN(s->burst_length, 32);
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tx_burst = (s->burst_length % 32) ? : 32;
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rx = 0;
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