Date: Thu, 14 May 2015 20:08:23 +0100
From: Mark Brown <broonie@kernel.org>
To: Scott Branden <sbranden@broadcom.com>
Cc: Jonathan Richardson <jonathar@broadcom.com>,
        Dmitry Torokhov <dtor@google.com>, Anatol Pomazau <anatol@google.com>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, linux-kernel@vger.kernel.org,
        linux-spi@vger.kernel.org,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
        devicetree@vger.kernel.org
Message-ID: <20150514190823.GR2761@sirena.org.uk>
References: <1431452293-16697-1-git-send-email-jonathar@broadcom.com>
 <1431452293-16697-3-git-send-email-jonathar@broadcom.com>
 <20150512191718.GW3066@sirena.org.uk>
 <5553E31A.8060309@broadcom.com>
 <5553E9FA.4070708@broadcom.com>
 <20150514103144.GO2761@sirena.org.uk>
 <5554E715.7070203@broadcom.com>
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Subject: Re: [PATCH 2/2] spi: bcm-mspi: Add support for Broadcom MSPI driver.
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On Thu, May 14, 2015 at 11:19:01AM -0700, Scott Branden wrote:
> On 15-05-14 03:31 AM, Mark Brown wrote:

> >Chip vendors often say this sort of thing and then get surprised by what
> >their users choose to do, and even if it only ever gets used with flash
> >all it would take is some new flash command which can use full duplex
> >for something.  Please write the code so it at least tries to handle
> >full duplex operation, if you can't test it fully that's not the end of
> >the world.  It doesn't look like it should be particularly difficult.

> Yes, there is always room for improvements in code.  In this case - it
> really is not worth our time to add code we can't test.  We try to deliver
> code that we can test and actually works.  Yes, if anyone needs to use the

While I try to not apply code that has obvious problems with silent data
corruption in it which is what we have just now.

> mspi for full duplex operation code can be added in the future - it is
> software.  This block has gone through many generations of our SoCs and has
> only been used for this purpose - the bootROM boots from this SPI only.  It
> is dedicated for this purpose.

All it takes is one hardware engineer who sees a SPI controller and a
GPIO they can use for chip select; I wouldn't be so sure that nobody
ever fixed this up locally (or happened to use a device that only needed
single duplex).

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