[PATCH v2] spi: spi-mem: ease checks in dtr_supports_op()

[Dhruva Gole]

Remove the extra conditions that cause some cases to fail prematurely
like if the data number of bytes is odd. The controller can handle odd
number of bytes data read in DTR Mode. Don't fail supports op for this
condition. This change can also be justified by taking a look at the
equivalent code in the linux kernel (v6.0.3), in drivers/spi/spi-mem.c,
where such an even number of data bytes check is absent as well.
The presence of this even byte check causes supports op failure even if
the controller can indeed work in case of odd bytes data reads in
DTR (Dual Transfer Rate) mode in xSPI.
There have not been any sort of major bugs in the absence of this
particular supports_op check, so it is safe to discard this
check from here.

Signed-off-by: Dhruva Gole <d-gole at ti.com>
---
v1 of the patch had a relatively shorter commit body that did not
sufficiently describe and justify this patch. link to v1:
https://lore.kernel.org/u-boot/20221020083424.86848-1-d-gole@ti.com/

v2 has just updated the commit body while preserving the code changes from
earlier v1 patch. This tries to address the changes requested from Jagan Teki.

 drivers/spi/spi-mem.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 8e8995fc537f..eecc13bec90d 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -181,10 +181,6 @@ bool spi_mem_dtr_supports_op(struct spi_slave *slave,
 	if (op->dummy.nbytes && op->dummy.buswidth == 8 && op->dummy.nbytes % 2)
 		return false;
 
-	if (op->data.dir != SPI_MEM_NO_DATA &&
-	    op->dummy.buswidth == 8 && op->data.nbytes % 2)
-		return false;
-
 	return spi_mem_check_buswidth(slave, op);
 }
 EXPORT_SYMBOL_GPL(spi_mem_dtr_supports_op);
-- 
2.25.1