linux-kernel - Re: [PATCH v2 2/2] mmc: sdhci-of-aspeed: add inversion sighttps://elixir.bootlin.com/linux/v4.6/ident/sdhci

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Message-ID: <d177ef37-643e-442d-d536-750e0bb5e86d@intel.com>
Date:   Fri, 15 Nov 2019 09:20:34 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Ivan Mikhaylov <i.mikhaylov@...ro.com>
Cc:     Joel Stanley <joel@....id.au>, Andrew Jeffery <andrew@...id.au>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org, openbmc@...ts.ozlabs.org
Subject: Re: [PATCH v2 2/2] mmc: sdhci-of-aspeed: add inversion
 sighttps://elixir.bootlin.com/linux/v4.6/ident/sdhci_opsnal presence

On 14/11/19 7:19 PM, Ivan Mikhaylov wrote:
> On Thu, 2019-11-14 at 15:10 +0200, Adrian Hunter wrote:
>> On 14/11/19 2:54 PM, Ivan Mikhaylov wrote:
>>> Change the default .get_cd callback. Add inverted signal card detection
>>> check.
>>>
>>> Signed-off-by: Ivan Mikhaylov <i.mikhaylov@...ro.com>
>>>
>>> diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-
>>> aspeed.c
>>> index 8962f6664381..186559ee8fcc 100644
>>> --- a/drivers/mmc/host/sdhci-of-aspeed.c
>>> +++ b/drivers/mmc/host/sdhci-of-aspeed.c
>>> @@ -143,6 +143,19 @@ static inline int aspeed_sdhci_calculate_slot(struct
>>> aspeed_sdhci *dev,
>>>  	return (delta / 0x100) - 1;
>>>  }
>>>  
>>> +static int aspeed_get_cd(struct mmc_host *mmc)
>>> +{
>>> +	struct sdhci_host *host = mmc_priv(mmc);
>>> +
>>> +	int present = !!(sdhci_readl(host, SDHCI_PRESENT_STATE)
>>> +			 & SDHCI_CARD_PRESENT);
>>> +
>>> +	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
>>> +		present = !present;
>>
>> Perhaps safer to flip the bit using CONFIG_MMC_SDHCI_IO_ACCESSORS and
>> ->readl() callback
>>
> 
> Sorry, don't quite understand what you're saying. You want to instantiate
> '.read_l' callback instead of '.get_cd' in sdhci_ops and substitute the real
> value?
> 
> res = readl(base, reg);
> if (reg == SDHCI_PRESENT_STATE)
> 	if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
> 		return !res;

Presumably just flip the SDHCI_CARD_PRESENT bit i.e.

		return res ^ SDHCI_CARD_PRESENT;

> return res;
> 
> Something like this?

Yes

> 
>>  
>>> +	host->mmc_host_ops.get_cd = aspeed_get_cd;
>>> +	if (of_property_read_bool(pdev->dev.of_node, "cd-inverted"))
>>> +		dev_info(&pdev->dev, "aspeed: sdhci: presence signal inversion
>>> enabled\n");
>>
>> Is this print really needed?
>>
> I can remove it if you think it's redundant.
> 
> Thanks.
> 
>