linux-kernel - Re: [PATCH 1/2] spi: ar934x: fix transfer size

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Date:   Wed, 22 Dec 2021 16:27:36 +0200
From:   Oskari Lemmelä <oskari@...mela.net>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] spi: ar934x: fix transfer size


On 22.12.2021 14.32, Mark Brown wrote:
> On Wed, Dec 22, 2021 at 07:59:57AM +0200, Oskari Lemmela wrote:
>> If bits_per_word is configured, transfer only word amount
>> of data per iteration.
> Does this actually materially affect what the hardware does?  How much
> data is transferred in an internal loop in the driver is completely
> immaterial, bits per word only matters for formatting of the transferred
> data.
I don't have logic analyzator to verify what hardware actual does.
I tested this with transferring 32bits to ATSAMD20J15 slave.
Running loop in 8bits or 16bits, transfer is done correctly without
any errors. When running loop in 24bits or 32bits directly I got
error from spi_sync_transfer.

Oskari