Re: [PATCH 0/5 RFC] mmc: sdhci-iproc: add bcm2835 support

From: Eric Anholt <eric@anholt.net>
To: Stefan Wahren <stefan.wahren@i2se.com>,
	Scott Branden <sbranden@broadcom.com>,
	Ray Jui <rjui@broadcom.com>, Lee Jones <lee@kernel.org>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Jon Mason <jonmason@broadcom.com>
Cc: kernel@martin.sperl.org, Rob Herring <robh+dt@kernel.org>,
	linux-mmc@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com,
	Arnd Bergmann <arnd@arndb.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	linux-rpi-kernel@lists.infradead.org, devicetree@vger.kernel.org
Subject: Re: [PATCH 0/5 RFC] mmc: sdhci-iproc: add bcm2835 support
Date: Thu, 28 Jan 2016 14:19:56 -0800	[thread overview]
Message-ID: <87mvrpfisz.fsf@eliezer.anholt.net> (raw)
In-Reply-To: <374314185.237972.d69bddce-8c03-4cf7-b6d6-f0cbd113f569.open-xchange@email.1und1.de>

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Stefan Wahren <stefan.wahren@i2se.com> writes:

>> Eric Anholt <eric@anholt.net> hat am 19. Januar 2016 um 22:00 geschrieben:
>>
>>
>> Stefan Wahren <stefan.wahren@i2se.com> writes:
>>
>> > This patch series based on the suggestion of Scott Branden to implement
>> > bcm2835 support into sdhci-iproc [1].
>> >
>> > These changes provide the following advantages:
>> > * no need to maintain a separate driver for bcm2835
>> > * improve support and test coverage of bcm2835 mmc support
>> > * get the rid of SDHCI_CAPABILITIES hack in bcm2835_sdhci_readl
>> > * increase write performance by avoiding delays in write ops
>> >
>> > Patch 1 and 2 adopt two sdhci-bcm2835 fixes to sdhci-iproc. The third patch
>> > tries to specify as much quirks as possible in the bcm283x.dtsi as possible.
>> > Patch 4 and 5 are the actually changes for bcm2835 support.
>> >
>> > These series has been tested on Raspberry Pi B with dd (direct I/O):
>> >
>> > sdhci-bcm2835
>> >
>> > 378 kB/s WRITE
>> > 10,6 MB/s READ
>> >
>> > sdhci-iproc (after applying patch series)
>> >
>> > 881 kB/s WRITE
>> > 10,8 MB/s READ
>>
>> I started a while ago at looking at merging the sdhost driver (for the
>> other controller on these boards that you can use instead), since
>> apparently the hardware's a better choice to use. This looks like a
>> really nice simplification for us for the Arasan mode, though. Would
>> you also want to delete the old 2835 driver after this series?
>
> Yes, that would be a necessary step. I don't know when it's the right time.
>
> What is the usual procedure for such a necessary driver?

If the kernel still supports the hardware, just in a different source
file, I don't see any problem with removing it immediately.

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