[LS1043ARDB] DSPI CS pin behavior

[randy_wang]

Dear All,

I added spi device TPM via ls1043ardb dspi.

TPM driver is OK and modprobe well.

bus can't get the respose.

and I capture the spi timing as following:

IN: MISO, OUT:MOSI,

And I compared another board, raspberry pi3, which the TPM works well on it, 

and captured the spi timing as following:

 

The difference is the spi chip select signal.

on the raspberry pi3, the CS is enabled all the way for entire transaction.

but on the ls1043ardb, the CS is disabled after the first 4 bytes.(Red circle mark)

does it meaning the CS should not be disabled right after the first 4 bytes?

if yes, how can I configure the SPI CS behavior?

Thanks.

[randy_wang]

Hi Pavel,

Thank you for your support.

I have solve this issue.

And port the Infineon TPM on LS1043 successfully.

the key points is:

TPM SPI driver encapsulates the first 4 bytes as a single message, and try to read status byte from another message, so it try to keep CS as assertion by setting cs_change to 1.

However, the NXP SPI driver will not set its dspi->cs_change value according the cs_change of transfer object passed by TPM SPI driver

Thanks.

[Pavel]

There is technical case (00189657) about this problem.

Please wait answer on this problem in this technical case.

Have a great day,
Pavel Chubakov

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