Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <1591277381-7734-1-git-send-email-vbadigan@codeaurora.org>
In-Reply-To: <1591277381-7734-1-git-send-email-vbadigan@codeaurora.org>
From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Mon, 8 Jun 2020 09:28:25 +0200
Message-ID: <CAPDyKFpO9afpONQEKgYBxwc2LtAn+31isoMGewOwR2Q8FnbCdA@mail.gmail.com>
Subject: Re: [RFC V1] mmc: core: Add partial initialization support
To:     Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
Cc:     Adrian Hunter <adrian.hunter@intel.com>,
        "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Maya Erez <merez@codeaurora.org>,
        Baolin Wang <baolin.wang@linaro.org>,
        Ludovic Barre <ludovic.barre@st.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Bradley Bolen <bradleybolen@gmail.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Thomas Gleixner <tglx@linutronix.de>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, 4 Jun 2020 at 15:30, Veerabhadrarao Badiganti
<vbadigan@codeaurora.org> wrote:
>
> From: Maya Erez <merez@codeaurora.org>
>
> This change adds the ability to partially initialize
> the MMC card by using card Sleep/Awake sequence (CMD5).
> Card will be sent to Sleep state during runtime/system suspend
> and will be woken up during runtime/system resume.
> By using this sequence the card doesn't need full initialization
> which gives time reduction in system/runtime resume path.

It would be nice if you could provide some more exact numbers of what
the gain is for a couple of different eMMCs, as to justify the change
a bit more.

Kind regards
Uffe

>
> Signed-off-by: Maya Erez <merez@codeaurora.org>
> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
> ---
>  drivers/mmc/core/mmc.c   | 146 ++++++++++++++++++++++++++++++++++++++++++++---
>  include/linux/mmc/card.h |   4 ++
>  include/linux/mmc/host.h |   2 +
>  3 files changed, 143 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index de94fbe629bd..5c6444113c92 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1892,7 +1892,13 @@ static int mmc_can_sleep(struct mmc_card *card)
>         return (card && card->ext_csd.rev >= 3);
>  }
>
> -static int mmc_sleep(struct mmc_host *host)
> +static int mmc_can_sleepawake(struct mmc_host *host)
> +{
> +       return host && (host->caps2 & MMC_CAP2_SLEEP_AWAKE) && host->card &&
> +               (host->card->ext_csd.rev >= 3);
> +}
> +
> +static int mmc_sleepawake(struct mmc_host *host, bool sleep)
>  {
>         struct mmc_command cmd = {};
>         struct mmc_card *card = host->card;
> @@ -1902,13 +1908,16 @@ static int mmc_sleep(struct mmc_host *host)
>         /* Re-tuning can't be done once the card is deselected */
>         mmc_retune_hold(host);
>
> -       err = mmc_deselect_cards(host);
> -       if (err)
> -               goto out_release;
> +       if (sleep) {
> +               err = mmc_deselect_cards(host);
> +               if (err)
> +                       goto out_release;
> +       }
>
>         cmd.opcode = MMC_SLEEP_AWAKE;
>         cmd.arg = card->rca << 16;
> -       cmd.arg |= 1 << 15;
> +       if (sleep)
> +               cmd.arg |= 1 << 15;
>
>         /*
>          * If the max_busy_timeout of the host is specified, validate it against
> @@ -1939,6 +1948,9 @@ static int mmc_sleep(struct mmc_host *host)
>         if (!cmd.busy_timeout || !(host->caps & MMC_CAP_WAIT_WHILE_BUSY))
>                 mmc_delay(timeout_ms);
>
> +       if (!sleep)
> +               err = mmc_select_card(card);
> +
>  out_release:
>         mmc_retune_release(host);
>         return err;
> @@ -2016,6 +2028,69 @@ static void mmc_detect(struct mmc_host *host)
>         }
>  }
>
> +static int mmc_cache_card_ext_csd(struct mmc_host *host)
> +{
> +       int err;
> +       u8 *ext_csd;
> +       struct mmc_card *card = host->card;
> +
> +       err = mmc_get_ext_csd(card, &ext_csd);
> +       if (err || !ext_csd) {
> +               pr_err("%s: %s: mmc_get_ext_csd failed (%d)\n",
> +                       mmc_hostname(host), __func__, err);
> +               return err;
> +       }
> +
> +       /* only cache read/write fields that the sw changes */
> +       card->ext_csd.raw_ext_csd_cmdq = ext_csd[EXT_CSD_CMDQ_MODE_EN];
> +       card->ext_csd.raw_ext_csd_cache_ctrl = ext_csd[EXT_CSD_CACHE_CTRL];
> +       card->ext_csd.raw_ext_csd_bus_width = ext_csd[EXT_CSD_BUS_WIDTH];
> +       card->ext_csd.raw_ext_csd_hs_timing = ext_csd[EXT_CSD_HS_TIMING];
> +
> +       kfree(ext_csd);
> +
> +       return 0;
> +}
> +
> +static int mmc_test_awake_ext_csd(struct mmc_host *host)
> +{
> +       int err;
> +       u8 *ext_csd;
> +       struct mmc_card *card = host->card;
> +
> +       err = mmc_get_ext_csd(card, &ext_csd);
> +       if (err) {
> +               pr_err("%s: %s: mmc_get_ext_csd failed (%d)\n",
> +                       mmc_hostname(host), __func__, err);
> +               return err;
> +       }
> +
> +       /* only compare read/write fields that the sw changes */
> +       pr_debug("%s: %s: type(cached:current) cmdq(%d:%d) cache_ctrl(%d:%d) bus_width (%d:%d) timing(%d:%d)\n",
> +               mmc_hostname(host), __func__,
> +               card->ext_csd.raw_ext_csd_cmdq,
> +               ext_csd[EXT_CSD_CMDQ_MODE_EN],
> +               card->ext_csd.raw_ext_csd_cache_ctrl,
> +               ext_csd[EXT_CSD_CACHE_CTRL],
> +               card->ext_csd.raw_ext_csd_bus_width,
> +               ext_csd[EXT_CSD_BUS_WIDTH],
> +               card->ext_csd.raw_ext_csd_hs_timing,
> +               ext_csd[EXT_CSD_HS_TIMING]);
> +
> +       err = !((card->ext_csd.raw_ext_csd_cmdq ==
> +                       ext_csd[EXT_CSD_CMDQ_MODE_EN]) &&
> +               (card->ext_csd.raw_ext_csd_cache_ctrl ==
> +                       ext_csd[EXT_CSD_CACHE_CTRL]) &&
> +               (card->ext_csd.raw_ext_csd_bus_width ==
> +                       ext_csd[EXT_CSD_BUS_WIDTH]) &&
> +               (card->ext_csd.raw_ext_csd_hs_timing ==
> +                       ext_csd[EXT_CSD_HS_TIMING]));
> +
> +       kfree(ext_csd);
> +
> +       return err;
> +}
> +
>  static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
>  {
>         int err = 0;
> @@ -2034,8 +2109,12 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
>         if (mmc_can_poweroff_notify(host->card) &&
>                 ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend))
>                 err = mmc_poweroff_notify(host->card, notify_type);
> -       else if (mmc_can_sleep(host->card))
> -               err = mmc_sleep(host);
> +       if (mmc_can_sleepawake(host)) {
> +               memcpy(&host->cached_ios, &host->ios, sizeof(host->cached_ios));
> +               mmc_cache_card_ext_csd(host);
> +       }
> +       if (mmc_can_sleep(host->card))
> +               err = mmc_sleepawake(host, true);
>         else if (!mmc_host_is_spi(host))
>                 err = mmc_deselect_cards(host);
>
> @@ -2048,6 +2127,43 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend)
>         return err;
>  }
>
> +static int mmc_partial_init(struct mmc_host *host)
> +{
> +       int err = 0;
> +       struct mmc_card *card = host->card;
> +
> +       mmc_set_bus_width(host, host->cached_ios.bus_width);
> +       mmc_set_timing(host, host->cached_ios.timing);
> +       if (host->cached_ios.enhanced_strobe) {
> +               host->ios.enhanced_strobe = true;
> +               if (host->ops->hs400_enhanced_strobe)
> +                       host->ops->hs400_enhanced_strobe(host, &host->ios);
> +       }
> +       mmc_set_clock(host, host->cached_ios.clock);
> +       mmc_set_bus_mode(host, host->cached_ios.bus_mode);
> +
> +       if (!mmc_card_hs400es(card) &&
> +                       (mmc_card_hs200(card) || mmc_card_hs400(card)))
> +               err = mmc_execute_tuning(card);
> +
> +       /*
> +        * The ext_csd is read to make sure the card did not went through
> +        * Power-failure during sleep period.
> +        * A subset of the W/E_P, W/C_P register will be tested. In case
> +        * these registers values are different from the values that were
> +        * cached during suspend, we will conclude that a Power-failure occurred
> +        * and will do full initialization sequence.
> +        */
> +       err = mmc_test_awake_ext_csd(host);
> +       if (err) {
> +               pr_debug("%s: %s: fail on ext_csd read (%d)\n",
> +                       mmc_hostname(host), __func__, err);
> +               goto out;
> +       }
> +out:
> +       return err;
> +}
> +
>  /*
>   * Suspend callback
>   */
> @@ -2070,7 +2186,7 @@ static int mmc_suspend(struct mmc_host *host)
>   */
>  static int _mmc_resume(struct mmc_host *host)
>  {
> -       int err = 0;
> +       int err = -EINVAL;
>
>         mmc_claim_host(host);
>
> @@ -2078,7 +2194,19 @@ static int _mmc_resume(struct mmc_host *host)
>                 goto out;
>
>         mmc_power_up(host, host->card->ocr);
> -       err = mmc_init_card(host, host->card->ocr, host->card);
> +
> +       if (mmc_can_sleepawake(host)) {
> +               err = mmc_sleepawake(host, false);
> +               if (!err)
> +                       err = mmc_partial_init(host);
> +               else
> +                       pr_err("%s: %s: awake failed (%d), fallback to full init\n",
> +                               mmc_hostname(host), __func__, err);
> +       }
> +
> +       if (err)
> +               err = mmc_init_card(host, host->card->ocr, host->card);
> +
>         mmc_card_clr_suspended(host->card);
>
>  out:
> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
> index cf3780a6ccc4..2f4c8d3d5763 100644
> --- a/include/linux/mmc/card.h
> +++ b/include/linux/mmc/card.h
> @@ -85,6 +85,8 @@ struct mmc_ext_csd {
>         unsigned int            data_tag_unit_size;     /* DATA TAG UNIT size */
>         unsigned int            boot_ro_lock;           /* ro lock support */
>         bool                    boot_ro_lockable;
> +       u8                      raw_ext_csd_cmdq;       /* 15 */
> +       u8                      raw_ext_csd_cache_ctrl; /* 33 */
>         bool                    ffu_capable;    /* Firmware upgrade support */
>         bool                    cmdq_en;        /* Command Queue enabled */
>         bool                    cmdq_support;   /* Command Queue supported */
> @@ -95,7 +97,9 @@ struct mmc_ext_csd {
>         u8                      raw_partition_support;  /* 160 */
>         u8                      raw_rpmb_size_mult;     /* 168 */
>         u8                      raw_erased_mem_count;   /* 181 */
> +       u8                      raw_ext_csd_bus_width;  /* 183 */
>         u8                      strobe_support;         /* 184 */
> +       u8                      raw_ext_csd_hs_timing;  /* 185 */
>         u8                      raw_ext_csd_structure;  /* 194 */
>         u8                      raw_card_type;          /* 196 */
>         u8                      raw_driver_strength;    /* 197 */
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index d4a50e5dc111..a69abe9f032b 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -375,6 +375,7 @@ struct mmc_host {
>  #define MMC_CAP2_CQE_DCMD      (1 << 24)       /* CQE can issue a direct command */
>  #define MMC_CAP2_AVOID_3_3V    (1 << 25)       /* Host must negotiate down from 3.3V */
>  #define MMC_CAP2_MERGE_CAPABLE (1 << 26)       /* Host can merge a segment over the segment size */
> +#define MMC_CAP2_SLEEP_AWAKE   (1 << 27)       /* Use Sleep/Awake (CMD5) */
>
>         int                     fixed_drv_type; /* fixed driver type for non-removable media */
>
> @@ -393,6 +394,7 @@ struct mmc_host {
>         spinlock_t              lock;           /* lock for claim and bus ops */
>
>         struct mmc_ios          ios;            /* current io bus settings */
> +       struct mmc_ios          cached_ios;
>
>         /* group bitfields together to minimize padding */
>         unsigned int            use_spi_crc:1;
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>