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Date:   Thu, 17 Sep 2020 14:16:32 +0900
From:   AKASHI Takahiro <takahiro.akashi@linaro.org>
To:     Adrian Hunter <adrian.hunter@intel.com>
Cc:     Ben Chuang <benchuanggli@gmail.com>, ulf.hansson@linaro.org,
        linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        ben.chuang@genesyslogic.com.tw, greg.tu@genesyslogic.com.tw
Subject: Re: [RFC PATCH V3 12/21] mmc: sdhci: UHS-II support, add hooks for
 additional operations
Message-ID: <20200917051632.GB3094018@laputa>
Mail-Followup-To: AKASHI Takahiro <takahiro.akashi@linaro.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Ben Chuang <benchuanggli@gmail.com>, ulf.hansson@linaro.org,
        linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        ben.chuang@genesyslogic.com.tw, greg.tu@genesyslogic.com.tw
References: <20200710111054.29562-1-benchuanggli@gmail.com>
 <9fa17d60-a540-d0d8-7b2c-0016c3b5c532@intel.com>
 <20200916080558.GA2978867@laputa>
 <6bf86b26-391a-0699-1818-d070357b9ddc@intel.com>
 <20200917023113.GB3071249@laputa>
 <255e030e-98e3-713a-a8fe-9f4c470c630f@intel.com>
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In-Reply-To: <255e030e-98e3-713a-a8fe-9f4c470c630f@intel.com>
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On Thu, Sep 17, 2020 at 07:52:03AM +0300, Adrian Hunter wrote:
> On 17/09/20 5:31 am, AKASHI Takahiro wrote:
> > Adrian,
> > 
> > On Wed, Sep 16, 2020 at 01:00:35PM +0300, Adrian Hunter wrote:
> >> On 16/09/20 11:05 am, AKASHI Takahiro wrote:
> >>> Adrian,
> >>>
> >>> Your comments are scattered over various functions, and so
> >>> I would like to address them in separate replies.
> >>>
> >>> First, I'd like to discuss sdhci_[add|remove]_host().
> >>>
> >>> On Fri, Aug 21, 2020 at 05:08:32PM +0300, Adrian Hunter wrote:
> >>>> On 10/07/20 2:10 pm, Ben Chuang wrote:
> >>>>> From: Ben Chuang <ben.chuang@genesyslogic.com.tw>
> >>>>>
> >>>>> In this commit, UHS-II related operations will be called via a function
> >>>>> pointer array, sdhci_uhs2_ops, in order to make UHS-II support as
> >>>>> a kernel module.
> >>>>> This array will be initialized only if CONFIG_MMC_SDHCI_UHS2 is enabled
> >>>>> and when the UHS-II module is loaded. Otherwise, all the functions
> >>>>> stay void.
> >>>>>
> >>>>> Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
> >>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> >>>>> ---
> >>>
> >>>  (snip)
> >>>
> >>>>>  		if (intmask & (SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE)) {
> >>>>>  			u32 present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
> >>>>>  				      SDHCI_CARD_PRESENT;
> >>>>> @@ -4717,6 +4812,14 @@ int sdhci_setup_host(struct sdhci_host *host)
> >>>>>  		/* This may alter mmc->*_blk_* parameters */
> >>>>>  		sdhci_allocate_bounce_buffer(host);
> >>>>>  
> >>>>> +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> >>>>> +	    host->version >= SDHCI_SPEC_400 &&
> >>>>> +	    sdhci_uhs2_ops.add_host) {
> >>>>> +		ret = sdhci_uhs2_ops.add_host(host, host->caps1);
> >>>>> +		if (ret)
> >>>>> +			goto unreg;
> >>>>> +	}
> >>>>> +
> >>>>
> >>>> I think you should look at creating uhs2_add_host() instead
> >>>>
> >>>>>  	return 0;
> >>>>>  
> >>>>>  unreg:
> >>>>> @@ -4738,6 +4841,8 @@ void sdhci_cleanup_host(struct sdhci_host *host)
> >>>>>  {
> >>>>>  	struct mmc_host *mmc = host->mmc;
> >>>>>  
> >>>>> +	/* FIXME: Do we have to do some cleanup for UHS2 here? */
> >>>>> +
> >>>>>  	if (!IS_ERR(mmc->supply.vqmmc))
> >>>>>  		regulator_disable(mmc->supply.vqmmc);
> >>>>>  
> >>>>> @@ -4766,6 +4871,14 @@ int __sdhci_add_host(struct sdhci_host *host)
> >>>>>  		mmc->cqe_ops = NULL;
> >>>>>  	}
> >>>>>  
> >>>>> +	if ((mmc->caps & MMC_CAP_UHS2) && !host->v4_mode) {
> >>>>> +		/* host doesn't want to enable UHS2 support */
> >>>>> +		mmc->caps &= ~MMC_CAP_UHS2;
> >>>>> +		mmc->flags &= ~MMC_UHS2_SUPPORT;
> >>>>> +
> >>>>> +		/* FIXME: Do we have to do some cleanup here? */
> >>>>> +	}
> >>>>> +
> >>>>>  	host->complete_wq = alloc_workqueue("sdhci", flags, 0);
> >>>>>  	if (!host->complete_wq)
> >>>>>  		return -ENOMEM;
> >>>>> @@ -4812,6 +4925,9 @@ int __sdhci_add_host(struct sdhci_host *host)
> >>>>>  unled:
> >>>>>  	sdhci_led_unregister(host);
> >>>>>  unirq:
> >>>>> +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> >>>>> +	    sdhci_uhs2_ops.remove_host)
> >>>>> +		sdhci_uhs2_ops.remove_host(host, 0);
> >>>>>  	sdhci_do_reset(host, SDHCI_RESET_ALL);
> >>>>>  	sdhci_writel(host, 0, SDHCI_INT_ENABLE);
> >>>>>  	sdhci_writel(host, 0, SDHCI_SIGNAL_ENABLE);
> >>>>> @@ -4869,6 +4985,10 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
> >>>>>  
> >>>>>  	sdhci_led_unregister(host);
> >>>>>  
> >>>>> +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> >>>>> +	    sdhci_uhs2_ops.remove_host)
> >>>>> +		sdhci_uhs2_ops.remove_host(host, dead);
> >>>>> +
> >>>>
> >>>> I think you should look at creating uhs2_remove_host() instead
> >>>
> >>> You suggest that we will have separate sdhci_uhs2_[add|remove]_host(),
> >>> but I don't think it's always convenient.
> >>>
> >>> UHS-II capable host will be set to call sdhci_uhs2_add_host() explicitly,
> >>> but we can't do that in case of pci and pltfm based drivers as they utilize
> >>> common helper functions, sdhci_pci_probe() and sdhci_pltfm_register(),
> >>> respectively.
> >>
> >> sdhci-pci has an add_host op
> >>
> >> sdhci_pltfm_init can be used instead of sdhci_pltfm_register
> >>
> >>
> >>> Therefore, we inevitably have to call sdhci_uhs2_add_host() there.
> >>>
> >>> If so, why should we distinguish sdhci_uhs2_add_host from sdhci_uhs_add_host?
> >>> I don't see any good reason.
> >>> Moreover, as a result, there exists a mixed usage of sdhci_ interfaces
> >>> and sdhci_uhs2_ interfaces in sdhci-pci-core.c and sdhci-pltfm.c.
> >>>
> >>> It sounds odd to me.
> >>
> >> It is already done that way for cqhci.
> > 
> > Okay, if it is your policy, I will follow that.
> > Then, I'm going to add
> > - remove_host field to struct sdhci_pci_fixes
> > - a controller specific helper function to each driver (only pci-gli for now)
> >   even though it looks quite generic.
> 
> If they seem generic then consider naming them
> sdhci_pci_uhs2_[add|remove]_host and putting them in sdhci-pci-core.c

So you don't mind that UHS-I and UHS-II code are mixed in sdhci-pci-core.c,
do you?

-Takahiro Akashi

> > 
> >   sdhci_gli_[add|remove]_host(struct sdhci_pci_slot *slot)
> >   {
> >       return sdhci_uhs2_[add|remove]_host(slot->host);
> >   }
> > 
> > # Or do you want to create a file like sdhci-uhs2-pci.c for those functions?
> 
> No
> 
> > 
> > -Takahiro Akashi
> > 
> >>>
> >>> -Takahiro Akashi
> >>>
> >>>
> >>>>
> >>>>>  	if (!dead)
> >>>>>  		sdhci_do_reset(host, SDHCI_RESET_ALL);
> >>>>>  
> >>>>>
> >>>>
> >>
>