Messages in this thread | | | Date | Thu, 3 Dec 2020 19:50:24 +0200 | From | Vladimir Oltean <> | Subject | Re: [PATCH] spi: spi-fsl-dspi: Add GPIO chip select support |
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Hi Maxim,
On Thu, Dec 03, 2020 at 08:12:19PM +0300, Максим Киселёв wrote: > From: Maxim Kiselev <bigunclemax@gmail.com> > Date: Thu, 3 Dec 2020 18:56:12 +0300 > Subject: [PATCH] spi: spi-fsl-dspi: Add GPIO chip select support > > This patch allows use of GPIO for the chip select. > Because dSPI controller can't send transactions without hardware chip > selects, so first unused native CS will be set in SPI_PUSHR_CMD_PCS
Are you sure?
From the reference manual:
SPIx_PUSHR bits 10–15 PCS: Select which PCS signals are to be asserted for the transfer. Refer to the chip-specific SPI information for the number of PCS signals used in this chip. 0 Negate the PCS[x] signal. 1 Assert the PCS[x] signal.
And the definition is:
#define SPI_PUSHR_CMD_PCS(x) (BIT(x) & GENMASK(5, 0))
Notice the BIT(x).
I expect that you can set the PCS to 0 and no hard chip select will assert.
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