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SubjectRe: [PATCH 1/2] spi: spi-mem: add spi_mem_dtr_supports_op()
Hi Pratyush,

Pratyush Yadav <> wrote on Thu, 4 Feb 2021 19:42:17 +0530:

> spi_mem_default_supports_op() rejects DTR ops by default to ensure that
> the controller drivers that haven't been updated with DTR support
> continue to reject them. It also makes sure that controllers that don't
> support DTR mode at all (which is most of them at the moment) also
> reject them.
> This means that controller drivers that want to support DTR mode can't
> use spi_mem_default_supports_op(). Driver authors have to roll their own
> supports_op() function and mimic the buswidth checks. See
> spi-cadence-quadspi.c for example. Or even worse, driver authors might
> skip it completely or get it wrong.
> Add spi_mem_dtr_supports_op(). It provides a basic sanity check for DTR
> ops and performs the buswidth requirement check. Move the logic for
> checking buswidth in spi_mem_default_supports_op() to a separate
> function so the logic is not repeated twice.
> Signed-off-by: Pratyush Yadav <>

I am not a SPI-NOR expert but for what I know this approach looks good
to me. Let's see what other maintainers think.

Reviewed-by: Miquel Raynal <>


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