-----Original Message-----
From: Bough Chen <haibo.chen@nxp.com>
Sent: Wednesday, September 1, 2021 1:35 PM
To: Kuldeep Singh <redacted>
Cc: linux-spi@vger.kernel.org; dl-linux-imx <redacted>; Rajesh
Bhagat [off-list ref]; broonie@kernel.org
Subject: RE: [EXT] [PATCH 3/4] spi: spi-nxp-fspi: add DDR mode support

quoted

-----Original Message-----
From: Kuldeep Singh
Sent: 2021年8月31日 18:42
To: Bough Chen <haibo.chen@nxp.com>
Cc: linux-spi@vger.kernel.org; dl-linux-imx <redacted>; Bough

Chen

quoted

[off-list ref]; Rajesh Bhagat [off-list ref];
broonie@kernel.org
Subject: RE: [EXT] [PATCH 3/4] spi: spi-nxp-fspi: add DDR mode support

Hi Haibo,

quoted

-----Original Message-----
From: haibo.chen@nxp.com <haibo.chen@nxp.com>
Sent: Friday, August 20, 2021 1:14 PM
To: Ashish Kumar <redacted>; yogeshgaur.83@gmail.com;
broonie@kernel.org
Cc: linux-spi@vger.kernel.org; dl-linux-imx <redacted>; Bough
Chen [off-list ref]
Subject: [EXT] [PATCH 3/4] spi: spi-nxp-fspi: add DDR mode support

Caution: EXT Email

From: Haibo Chen <haibo.chen@nxp.com>

For LUT, add DDR command support.
Also use new API spi_mem_dtr_supports_op() to check the DTR mode.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>

Thanks for submitting patch to support octal DTR.

quoted

---
 drivers/spi/spi-nxp-fspi.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-nxp-fspi.c b/drivers/spi/spi-nxp-fspi.c

index
a764eb475aed..f7acad2cbe64 100644

--- a/drivers/spi/spi-nxp-fspi.c
+++ b/drivers/spi/spi-nxp-fspi.c

@@ -486,6 +486,9 @@ static bool nxp_fspi_supports_op(struct spi_mem

*mem,
            op->data.nbytes > f->devtype_data->txfifo)
                return false;

+       if (op->cmd.dtr && op->addr.dtr && op->dummy.dtr &&

op->data.dtr)

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+               return spi_mem_dtr_supports_op(mem, op);
+

[snip]

Now that spi-nor framework and flexspi driver supports octal DTR, if
device-tree specifies RX and TX bus-width as <8,8> , then above change

will

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always make sure to select DTR mode and SDR will never get selected.
Please note, Layerscape LX2160A and LX2162A are two platforms which have
micron mt35xu512aba (support octal dtr) and are causing probe failure with
these patches as required dependencies for enabling DTR are not met.

Since framework selects maximum supported capability, I think there should

be

quoted

a mechanism to choose SDR or DTR mode in driver itself.
This will also help for a platform to fallback from DTR to SDR in case DTR
doesn't work.
We can enable this feature as a quirk or by reading a property from

device-tree.

quoted

Please let me know your views.

Thanks for your comments!
The flexspi controller in Layerscape support 8bit DTR, but for flexspi, if
support 8bit DTR, need to use mode3, which means we must connect the DQS
pad
on board.
Seems LX216x board do not connect DQS line.
We should take this into consideration, this is board limitation, better to
involve a property in device-tree.
I will send a V2 patch soon.

Thanks for your understanding.
I will make sure to confirm NXP layerscape devices for next version of series.

Regards
Kuldeep