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Date:   Thu, 24 Sep 2020 18:35:38 +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: <20200924093538.GA35720@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>
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In-Reply-To: <9fa17d60-a540-d0d8-7b2c-0016c3b5c532@intel.com>
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Adrian,

This is, hopefully, my last reply to your comments on this patch#12.

Regarding _request() and _send_command() (and more),

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.
> > 
  (snip)

> Again, this is what I want to avoid.  I would like to have 3 kinds of functions:
> 	- SD mode only
> 	- UHS-II only
> 	- SD functions with no UHS-II code, that can also be used by UHS-II
> i.e. I don't want to mix UHS-II code and SD mode code in the same function.
> 
> I think sdhci-uhs2.c should provide a request function and a send_command function.
> I would start by removing everything you may not need, and then see if you have any problems.
> e.g.
> 
> void uhs2_request(struct mmc_host *mmc, struct mmc_request *mrq)
> {
> 	struct sdhci_host *host = mmc_priv(mmc);
> 	struct mmc_command *cmd;
> 	unsigned long flags;
> 
> 	if (!host->uhs2_mode) {
> 		sdhci_request(mmc, mrq);
> 		return;
> 	}
> 
> 	spin_lock_irqsave(&host->lock, flags);
> 	uhs2_send_command(host, cmd);
> 	spin_unlock_irqrestore(&host->lock, flags);
> }
> EXPORT_SYMBOL_GPL(uhs2_request);
> 
> For sdhci_prepare_data(), I would factor out the dma part, so
> 
> static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
> {
> 	struct mmc_data *data = cmd->data;
> 
> 	sdhci_initialize_data(host, data);
> 
> 	sdhci_prepare_dma(host, data);
> 
> 	sdhci_set_block_info(host, data);
> }
> 
> The you could export sdhci_initialize_data() and sdhci_prepare_dma() for uhs2.
> 
> >  }
> >  
> >  #if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
> > @@ -1439,6 +1463,13 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
> >  	u16 mode = 0;
> >  	struct mmc_data *data = cmd->data;
> >  
> > +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +	    host->mmc->flags & MMC_UHS2_SUPPORT) {
> > +		if (sdhci_uhs2_ops.set_transfer_mode)
> > +			sdhci_uhs2_ops.set_transfer_mode(host, cmd);
> > +		return;
> > +	}
> > +
> 
> Once you provide uhs2_request() and uhs2_send_command(), the transfer mode setting can be done in sdhci-uhs2.c

If I try to make changes as you suggested above, a lot of other uhs2-flavored
functions will also be created due to calling dependency/sequences
and for "completeness" compared to uhs counterparts.
They probably include
    sdhci_uhs2_prepare_data()
    sdhci_uhs2_external_dma_prepare_data()
    sdhci_uhs2_send_command()
    sdhci_uhs2_send_command_try()
    sdhci_uhs2_send_tuning()
    sdhci_uhs2_request()
    sdhci_uhs2_request_atomic()
    sdhci_uhs2_thread_irq()
    sdhci_uhs2_irq()
    sdhci_uhs2_cmd_irq()
    sdhci_uhs2_finish_command()
    sdhci_uhs2_resume_host()
    __sdhci_uhs2_add_host()
    sdhci_uhs2_add_host()
(Some may not be used under the current drivers.)

In addition, a bunch of functions in sdhci.c will also have to be exported
to uhs2 as "global" functions instead of "static."

Is this all that you expect to see?

-Takahiro Akashi


> >  	if (data == NULL) {
> >  		if (host->quirks2 &
> >  			SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD) {
> > @@ -1570,6 +1601,12 @@ static void __sdhci_finish_data(struct sdhci_host *host, bool sw_data_timeout)
> >  	else
> >  		data->bytes_xfered = data->blksz * data->blocks;
> >  
> > +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +	    host->mmc->flags & MMC_UHS2_INITIALIZED) {
> > +		__sdhci_finish_mrq(host, data->mrq);
> > +		return;
> > +	}
> 
> At least to start with, I think it would be better to handle UHS-II cmd and data interrupts completely in sdhci-uhs2.c
> 
> > +
> >  	/*
> >  	 * Need to send CMD12 if -
> >  	 * a) open-ended multiblock transfer not using auto CMD12 (no CMD23)
> > @@ -1654,7 +1691,8 @@ static bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
> >  			sdhci_prepare_data(host, cmd);
> >  	}
> >  
> > -	sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
> > +	if (!IS_ENABLED(CONFIG_MMC_SDHCI_UHS2))
> > +		sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
> 
> Not needed when instead you provide uhs2_send_command() 
> >  
> >  	sdhci_set_transfer_mode(host, cmd);
> >  
> > @@ -1699,6 +1737,17 @@ static bool sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
> >  	if (host->use_external_dma)
> >  		sdhci_external_dma_pre_transfer(host, cmd);
> >  
> > +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +	    (host->mmc->flags & MMC_UHS2_SUPPORT)) {
> > +		if (sdhci_uhs2_ops.send_command)
> > +			sdhci_uhs2_ops.send_command(host, cmd);
> > +
> > +		return true;
> > +	}
> > +
> > +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2))
> > +		sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
> 
> Not needed when instead you provide uhs2_send_command()
> 
> > +
> >  	sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);
> >  
> >  	return true;
> > @@ -1780,13 +1829,20 @@ static void sdhci_finish_command(struct sdhci_host *host)
> >  {
> >  	struct mmc_command *cmd = host->cmd;
> >  
> > -	host->cmd = NULL;
> > +	if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +	    host->mmc->flags & MMC_UHS2_SUPPORT) {
> > +		if (sdhci_uhs2_ops.finish_command)
> > +			sdhci_uhs2_ops.finish_command(host);
> > +	} else {
> > +		host->cmd = NULL;
> >  
> > -	if (cmd->flags & MMC_RSP_PRESENT) {
> > -		if (cmd->flags & MMC_RSP_136) {
> > -			sdhci_read_rsp_136(host, cmd);
> > -		} else {
> > -			cmd->resp[0] = sdhci_readl(host, SDHCI_RESPONSE);
> > +		if (cmd->flags & MMC_RSP_PRESENT) {
> > +			if (cmd->flags & MMC_RSP_136) {
> > +				sdhci_read_rsp_136(host, cmd);
> > +			} else {
> > +				cmd->resp[0] = sdhci_readl(host,
> > +							   SDHCI_RESPONSE);
> > +			}
> 
> At least to start with, I think it would be better to handle UHS-II cmd and data interrupts completely in sdhci-uhs2.c
> 
> >  		}
> >  	}
> >  
> > @@ -1809,6 +1865,7 @@ static void sdhci_finish_command(struct sdhci_host *host)
> >  		} else if (!(host->quirks & SDHCI_QUIRK_NO_BUSY_IRQ) &&
> >  			   cmd == host->data_cmd) {
> >  			/* Command complete before busy is ended */
> > +			host->cmd = NULL;
> 
> host->cmd is set to NULL at the start of this function, so this is not needed.
> 
> >  			return;
> >  		}
> >  	}
> > @@ -1828,6 +1885,8 @@ static void sdhci_finish_command(struct sdhci_host *host)
> >  		if (!cmd->data)
> >  			__sdhci_finish_mrq(host, cmd->mrq);
> >  	}
> > +
> > +	host->cmd = NULL;
> 
> host->cmd is set to NULL at the start of this function, so this is not needed.
> 
> >  }
> >  
> >  static u16 sdhci_get_preset_value(struct sdhci_host *host)
> > @@ -1855,6 +1914,11 @@ static u16 sdhci_get_preset_value(struct sdhci_host *host)
> >  	case MMC_TIMING_MMC_HS400:
> >  		preset = sdhci_readw(host, SDHCI_PRESET_FOR_HS400);
> >  		break;
> > +#if IS_ENABLED(CONFIG_MMC_SDHCI_UHS2)
> 
> Shouldn't need conditional compilation for this
> 
> > +	case MMC_TIMING_UHS2:
> > +		preset = sdhci_readw(host, SDHCI_PRESET_FOR_UHS2);
> > +		break;
> > +#endif
> >  	default:
> >  		pr_warn("%s: Invalid UHS-I mode selected\n",
> >  			mmc_hostname(host->mmc));
> > @@ -2095,7 +2159,6 @@ void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> >  			sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
> >  
> >  		pwr |= SDHCI_POWER_ON;
> > -
> 
> No white space changes mixed in please
> 
> >  		sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
> >  
> >  		if (host->quirks2 & SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON)
> > @@ -2261,6 +2324,7 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >  {
> >  	struct sdhci_host *host = mmc_priv(mmc);
> >  	u8 ctrl;
> > +	u16 ctrl_2;
> >  
> >  	if (ios->power_mode == MMC_POWER_UNDEFINED)
> >  		return;
> > @@ -2287,6 +2351,10 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >  		sdhci_enable_preset_value(host, false);
> >  
> >  	if (!ios->clock || ios->clock != host->clock) {
> > +		if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +		    ios->timing == MMC_TIMING_UHS2)
> > +			host->timing = ios->timing;
> > +
> >  		host->ops->set_clock(host, ios->clock);
> >  		host->clock = ios->clock;
> >  
> > @@ -2308,6 +2376,18 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >  	else
> >  		sdhci_set_power(host, ios->power_mode, ios->vdd);
> >  
> > +	/* 4.0 host support */
> > +	if (host->version >= SDHCI_SPEC_400) {
> > +		/* UHS2 Support */
> > +		if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +		    host->mmc->flags & MMC_UHS2_SUPPORT &&
> > +		    host->mmc->caps & MMC_CAP_UHS2) {
> > +			if (sdhci_uhs2_ops.do_set_ios)
> > +				sdhci_uhs2_ops.do_set_ios(host, ios);
> > +			return;
> > +		}
> > +	}
> > +
> 
> Please look at using existing callbacks instead, maybe creating uhs2_set_ios(), uhs2_set_clock(), uhs2_set_power()
> 
> >  	if (host->ops->platform_send_init_74_clocks)
> >  		host->ops->platform_send_init_74_clocks(host, ios->power_mode);
> >  
> > @@ -2331,7 +2411,7 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >  	}
> >  
> >  	if (host->version >= SDHCI_SPEC_300) {
> > -		u16 clk, ctrl_2;
> > +		u16 clk;
> >  
> >  		if (!host->preset_enabled) {
> >  			sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> > @@ -3173,11 +3253,19 @@ static bool sdhci_request_done(struct sdhci_host *host)
> >  			/* This is to force an update */
> >  			host->ops->set_clock(host, host->clock);
> >  
> > -		/* Spec says we should do both at the same time, but Ricoh
> > -		   controllers do not like that. */
> > -		sdhci_do_reset(host, SDHCI_RESET_CMD);
> > -		sdhci_do_reset(host, SDHCI_RESET_DATA);
> > -
> > +		if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +		    host->mmc->flags & MMC_UHS2_INITIALIZED) {
> > +			if (sdhci_uhs2_ops.reset)
> > +				sdhci_uhs2_ops.reset(host,
> > +						     SDHCI_UHS2_SW_RESET_SD);
> > +		} else {
> > +			/*
> > +			 * Spec says we should do both at the same time, but
> > +			 * Ricoh controllers do not like that.
> > +			 */
> > +			sdhci_do_reset(host, SDHCI_RESET_CMD);
> > +			sdhci_do_reset(host, SDHCI_RESET_DATA);
> > +		}
> 
> Please look at using the existing ->reset() sdhci host op instead.
> 
> >  		host->pending_reset = false;
> >  	}
> >  
> > @@ -3532,6 +3620,13 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id)
> >  				  SDHCI_INT_BUS_POWER);
> >  		sdhci_writel(host, mask, SDHCI_INT_STATUS);
> >  
> > +		if (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) &&
> > +		    intmask & SDHCI_INT_ERROR &&
> > +		    host->mmc->flags & MMC_UHS2_SUPPORT) {
> > +			if (sdhci_uhs2_ops.irq)
> > +				sdhci_uhs2_ops.irq(host);
> > +		}
> > +
> 
> Please look at using the existing ->irq() sdhci host op instead
> 
> >  		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
> 
> >  	if (!dead)
> >  		sdhci_do_reset(host, SDHCI_RESET_ALL);
> >  
> > 
>