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Subject: Re: [PATCH 0/2] mmc: mmci: add quirk property to add stm32 transfer
 mode
To:     Russell King - ARM Linux admin <linux@armlinux.org.uk>
CC:     <devicetree@vger.kernel.org>, Ulf Hansson <ulf.hansson@linaro.org>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        <linux-mmc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        <srinivas.kandagatla@linaro.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>
References: <1550743851-13588-1-git-send-email-ludovic.Barre@st.com>
 <20190221102739.cc37au6elqu6gvfe@shell.armlinux.org.uk>
 <20190221103049.tspc5igoe6wmt3jd@shell.armlinux.org.uk>
From:   Ludovic BARRE <ludovic.barre@st.com>
Message-ID: <a736b773-d6e6-eb81-90d6-ebeab7b401cb@st.com>
Date:   Thu, 21 Feb 2019 14:38:36 +0100
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hi Russell & Ulf

On 2/21/19 11:30 AM, Russell King - ARM Linux admin wrote:
> On Thu, Feb 21, 2019 at 10:27:39AM +0000, Russell King - ARM Linux admin wrote:
>> On Thu, Feb 21, 2019 at 11:10:49AM +0100, Ludovic Barre wrote:
>>> From: Ludovic Barre <ludovic.barre@st.com>
>>>
>>> This patch series introduces a bitmap of hardware quirks that require
>>> some special action. This should reduce the number of boolean
>>> into variant structure.
>>> And adds quirk bit to define sdmmc specific transfer modes.
>>
>> Please find some other way to deal with these differences.  As far as
>> I'm concerned, introducing a quirk bitmask such as what was done in
>> sdhci is a complete disaster and leads to long-term maintanability
>> problems.
>>
>> We already have a way to deal with variants in mmci.
> 
> ... to finish what I was saying ...
> 
> and I think that:
> 
>          if (variant->blksz_datactrl16)
>                  datactrl = variant->datactrl_dpsm_enable | (data->blksz << 16);
>          else if (variant->blksz_datactrl4)
>                  datactrl = variant->datactrl_dpsm_enable | (data->blksz << 4);
>          else
>                  datactrl = variant->datactrl_dpsm_enable | blksz_bits << 4;
> 
> ought to become a variant function call which returns the appropriate
> datactrl value.  This would shrink the amount of variant testing in this
> path, and also means that going forward we aren't facing an endlessly
> increasing number of tests here.

For blksz_datactrl case:
We could create an inline function for datactrl16 and blksz_datactrl4
which returns the appropriate datactrl value (specific for ux500v2 and 
qcom). This function could be register in mmci_host_ops structure.

in mmci_start_data function we could call a common function which call a
hook if defined.

int mmci_dblksz(struct mmci_host *host)
{
	if (host->ops && host->ops->dblksz)
		return host->ops->dblk(host);

	/* default data block size definition */
	blksz_bits = ffs(data->blksz) - 1;
	return blksz_bits << 4;
}

what do you think about it?
After, I'm afraid to multiply callback function in mmci_host_ops.

For stm32 transfer mode:
ditto, a callback function or I keep a boolean?

BR
Ludo

> 
>>
>>>
>>> Ludovic Barre (2):
>>>    mmc: mmci: introduce a quirks property into variant struct
>>>    mmc: mmci: add quirk property to add stm32 transfer mode
>>>
>>>   drivers/mmc/host/mmci.c | 11 +++++++++++
>>>   drivers/mmc/host/mmci.h |  9 +++++++++
>>>   2 files changed, 20 insertions(+)
>>>
>>> -- 
>>> 2.7.4
>>>
>>>
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> linux-arm-kernel@lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>>
>>
>> -- 
>> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
>> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
>> According to speedtest.net: 11.9Mbps down 500kbps up
>>
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>>
>