From: Vladimir Oltean <olteanv@gmail.com>
To: Mark Brown <broonie@kernel.org>
Cc: Jakub Kicinski <kuba@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, Florian Fainelli <f.fainelli@gmail.com>,
Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
linux-spi@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>,
Vladimir Oltean <vladimir.oltean@nxp.com>
Subject: Re: [PATCH v3 net-next 1/2] net: dsa: sja1105: send multiple spi_messages instead of using cs_change
Date: Mon, 24 May 2021 16:02:12 +0300 [thread overview]
Message-ID: <20210524130212.g6jcf7y4grc64mki@skbuf> (raw)
In-Reply-To: <20210524083529.GA4318@sirena.org.uk>
On Mon, May 24, 2021 at 09:35:29AM +0100, Mark Brown wrote:
> On Fri, May 21, 2021 at 12:16:56AM +0300, Vladimir Oltean wrote:
>
> > The fact of the matter is that spi_max_message_size() has an ambiguous
> > meaning if any non-final transfer has cs_change = true.
>
> This is not the case, spi_message_max_size() is a limit on the size of a
> spi_message.
That is true, although it doesn't mean much, since in the presence of
cs_change, a spi_message has no correspondent in the physical world
(i.e. you can't look at a logic analyzer dump and say "this spi_message
was from this to this point"), and that is the problem really.
Describing the controller's inability to send more than N SPI words with
continuous chip select using spi_message_max_size() is what seems flawed
to me, but it's what we have, and what I've adapted to.
next prev parent reply other threads:[~2021-05-24 13:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 21:16 [PATCH v3 net-next 0/2] Adapt the sja1105 DSA driver to the SPI controller's transfer limits Vladimir Oltean
2021-05-20 21:16 ` [PATCH v3 net-next 1/2] net: dsa: sja1105: send multiple spi_messages instead of using cs_change Vladimir Oltean
2021-05-24 8:35 ` Mark Brown
2021-05-24 13:02 ` Vladimir Oltean [this message]
2021-06-07 17:56 ` Mark Brown
2021-05-20 21:16 ` [PATCH v3 net-next 2/2] net: dsa: sja1105: adapt to a SPI controller with a limited max transfer size Vladimir Oltean
2021-05-21 20:30 ` [PATCH v3 net-next 0/2] Adapt the sja1105 DSA driver to the SPI controller's transfer limits patchwork-bot+netdevbpf
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