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Message-ID: <CACT4zj9LuJoy9mX4Fqm+jZf1bDa5oUZcR6mPa-otW1mXfNLh1g@mail.gmail.com>
Date: Thu, 17 Sep 2020 18:12:27 +0800
From: Ben Chuang <benchuanggli@...il.com>
To: AKASHI Takahiro <takahiro.akashi@...aro.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Ben Chuang <benchuanggli@...il.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
linux-mmc <linux-mmc@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Ben Chuang <ben.chuang@...esyslogic.com.tw>,
greg.tu@...esyslogic.com.tw
Cc: Renius.Chen@...esyslogic.com.tw
Subject: Re: [RFC PATCH V3 12/21] mmc: sdhci: UHS-II support, add hooks for
additional operations
Hi Takahiro,
On Thu, Sep 17, 2020 at 1:12 PM AKASHI Takahiro
<takahiro.akashi@...aro.org> wrote:
>
> Adrian, Ben,
>
> Regarding _reset() function,
>
> 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@...esyslogic.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@...esyslogic.com.tw>
> > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> > > ---
> > > drivers/mmc/host/sdhci.c | 152 ++++++++++++++++++++++++++++++++++-----
> > > 1 file changed, 136 insertions(+), 16 deletions(-)
> > >
>
> (snip)
>
> > > 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.
>
> Well, the second argument to those reset functions is a bit-wise value
> to different "reset" registers, SDHCI_SOFTWARE_RESET and SDHCI_UHS2_SW_RESET,
> respectively.
>
> This fact raises a couple of questions to me:
>
> 1) Does it make sense to merge two functionality into one, i.e.
> sdhci_do_reset(), which is set to call ->reset hook?
>
> -> Adrian
>
> 2) UHS2_SW_RESET_SD is done only at this place while there are many callsites
> of reset(RESET_CMD|RESET_DATA) in sdhci.c.
> Why does the current code work?
>
> I found, in sdhci-pci-gli.c,
> sdhci_gl9755_reset()
> /* reset sd-tran on UHS2 mode if need to reset cmd/data */
> if ((mask & SDHCI_RESET_CMD) | (mask & SDHCI_RESET_DATA))
> gl9755_uhs2_reset_sd_tran(host);
>
> Is this the trick to avoid the issue?
> (It looks redundant in terms of the hack above in sdhci_request_done()
> and even quite dirty to me. Moreover, no corresponding code for gl9750
> and gl9763.)
GL9755 currently does SD reset and UHS-II reset together.
There is no UHS-II interface on gl9750 and gl9763e.
>
> -> Ben
>
> 3) (More or less SD specification issue)
> In UHS-II mode, do we have to call reset(SHCI_RESET_ALL) along with
> reset(UHS2_SW_RESET_FULL)?
> Under the current implementation, both will be called at the end.
>
As I know, the UHS2_SW_RESET_FULL is only for UHS-II.
Can you list the lines that reset(SHCI_RESET_ALL) and
reset(UHS2_SW_RESET_FULL) are both called?
> -> Adrian, Ben
>
> 4) (Not directly linked to UHS-II support)
> In some places, we see the sequence:
> sdhci_do_reset(host, SDHCI_RESET_CMD);
> sdhci_do_reset(host, SDHCI_RESET_DATA);
> while in other places,
> sdhci_do_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
>
> If the statement below is true,
> > > - /* Spec says we should do both at the same time, but Ricoh
> > > - controllers do not like that. */
> the latter should be wrong.
>
> -> Adrian
>
> -Takahiro Akashi
>
>
>
> > > 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);
> > >
> > >
> >
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