Subject: Re: [PATCH 1/2] spi: ar934x: fix transfer size
To:     Mark Brown <broonie@kernel.org>
Cc:     linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20211222055958.1383233-1-oskari@lemmela.net>
 <20211222055958.1383233-2-oskari@lemmela.net>
 <YcMa1TIg3x3oBKBl@sirena.org.uk>
From:   =?UTF-8?Q?Oskari_Lemmel=c3=a4?= <oskari@lemmela.net>
Message-ID: <98a574a2-45c3-5d7c-6405-0cd279a81816@lemmela.net>
Date:   Wed, 22 Dec 2021 16:27:36 +0200
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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