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Date: Fri, 7 Nov 2014 10:31:34 -0800
From: Scott Branden <sbranden@broadcom.com>
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To: Stephen Warren <swarren@wwwdotorg.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        "Peter Griffin" <peter.griffin@linaro.org>,
        Chris Ball <chris@printf.net>, "Piotr Krol" <pietrushnic@gmail.com>
CC: <linux-mmc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Joe Perches <joe@perches.com>, <linux-rpi-kernel@lists.infradead.org>,
        Ray Jui <rjui@broadcom.com>, <bcm-kernel-feedback-list@broadcom.com>
Subject: Re: [PATCHv2 4/5] mmc: shdci-bcm2835: add verify for 32-bit back-to-back
 workaround
References: <Scott Branden <sbranden@broadcom.com> <1414651017-3545-1-git-send-email-sbranden@broadcom.com> <1414651017-3545-5-git-send-email-sbranden@broadcom.com> <5459AECF.8000402@wwwdotorg.org> <5459CB17.3020303@broadcom.com> <545B00B9.5090108@wwwdotorg.org>
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On 14-11-05 09:01 PM, Stephen Warren wrote:
> On 11/05/2014 12:00 AM, Scott Branden wrote:
>> On 14-11-04 08:59 PM, Stephen Warren wrote:
>>> On 10/30/2014 12:36 AM, Scott Branden wrote:
>>>> Add a verify option to driver to print out an error message if a
>>>> potential back to back write could cause a clock domain issue.
>>>
>>>> index f8c450a..11af27f 100644
>>>
>>>> +#ifdef CONFIG_MMC_SDHCI_BCM2835_VERIFY_WORKAROUND
>>>> +    struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>>> +    struct bcm2835_sdhci_host *bcm2835_host = pltfm_host->priv;
>>>> +
>>>> +    if (bcm2835_host->previous_reg == reg) {
>>>> +        if ((reg != SDHCI_HOST_CONTROL)
>>>> +            && (reg != SDHCI_CLOCK_CONTROL)) {
>>>
>>> The comment in patch 3 says the problem doesn't apply to the data
>>> register. Why does this check for these two registers rather than data?
>> This Verify workaround patch still a work in progress.  I'm still
>> getting more info from the silicon designers on the back-to-back
>> register writes that are affect.  The spew of 0x20 or 0x28 or 0x2c
>> register writes are all ok locations that don't need to be worked
>> around.  This patch needs to be corrected with the proper register rules
>> still.
Thanks for testing.  Yes, I have work to do on the verify patch above still.
>
> FYI, I applied the series except for this patch, and everything
> /appeared/ to work OK for a brief test (boot, log in, reboot). Still,
> I'll hold off my Tested-by/acked-by until the comment in patch 3 and the
> register list above match, and there's no log spew with everything applied.
>