linux-kernel - Re: [PATCH V12 10/23] mmc: sdhci-uhs2: add reset function and uhs2

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Message-ID: <CAPDyKFrynugse6+vwummTQ73egwvGAfKreH=iihv9bhFN1SJYQ@mail.gmail.com>
Date:   Tue, 3 Oct 2023 12:30:16 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Victor Shih <victorshihgli@...il.com>
Cc:     adrian.hunter@...el.com, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, benchuanggli@...il.com,
        HL.Liu@...esyslogic.com.tw, Greg.tu@...esyslogic.com.tw,
        takahiro.akashi@...aro.org, dlunev@...omium.org,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>,
        Victor Shih <victor.shih@...esyslogic.com.tw>
Subject: Re: [PATCH V12 10/23] mmc: sdhci-uhs2: add reset function and
 uhs2_mode function

On Fri, 15 Sept 2023 at 11:44, Victor Shih <victorshihgli@...il.com> wrote:
>
> From: Victor Shih <victor.shih@...esyslogic.com.tw>
>
> Sdhci_uhs2_reset() does a UHS-II specific reset operation.
>
> Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> Signed-off-by: Victor Shih <victor.shih@...esyslogic.com.tw>
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>
> Updates in V8:
>  - Adjust the position of matching brackets.
>
> Updates in V6:
>  - Remove unnecessary functions and simplify code.
>
> ---
>
>  drivers/mmc/host/sdhci-uhs2.c | 45 +++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci-uhs2.h |  2 ++
>  2 files changed, 47 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> index e339821d3504..dfc80a7f1bad 100644
> --- a/drivers/mmc/host/sdhci-uhs2.c
> +++ b/drivers/mmc/host/sdhci-uhs2.c
> @@ -10,7 +10,9 @@
>   *  Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
>   */
>
> +#include <linux/delay.h>
>  #include <linux/module.h>
> +#include <linux/iopoll.h>
>
>  #include "sdhci.h"
>  #include "sdhci-uhs2.h"
> @@ -49,6 +51,49 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host)
>  }
>  EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);
>
> +/*****************************************************************************\
> + *                                                                           *
> + * Low level functions                                                       *
> + *                                                                           *
> +\*****************************************************************************/
> +
> +bool sdhci_uhs2_mode(struct sdhci_host *host)
> +{
> +       return host->mmc->flags & MMC_UHS2_SUPPORT;

The MMC_UHS2_SUPPORT bit looks redundant to me. Instead, I think we
should be using mmc->ios.timings, which already indicates whether we
are using UHS2 (MMC_TIMING_UHS2_SPEED_*). See patch2 where we added
this.

That said, I think we should drop the sdhci_uhs2_mode() function
altogether and instead use mmc_card_uhs2(), which means we should move
it to include/linux/mmc/host.h, so it becomes available for host
drivers.

> +}
> +
> +/**
> + * sdhci_uhs2_reset - invoke SW reset
> + * @host: SDHCI host
> + * @mask: Control mask
> + *
> + * Invoke SW reset, depending on a bit in @mask and wait for completion.
> + */
> +void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
> +{
> +       unsigned long timeout;
> +       u32 val;
> +
> +       sdhci_writew(host, mask, SDHCI_UHS2_SW_RESET);
> +
> +       if (mask & SDHCI_UHS2_SW_RESET_FULL)
> +               host->clock = 0;
> +
> +       /* Wait max 100 ms */
> +       timeout = 100000;

Please convert into using a define and use that directly, below instead.

> +
> +       /* hw clears the bit when it's done */
> +       if (read_poll_timeout_atomic(sdhci_readw, val, !(val & mask), 10,
> +                                    timeout, true, host, SDHCI_UHS2_SW_RESET)) {
> +               pr_err("%s: %s: Reset 0x%x never completed.\n", __func__,
> +                      mmc_hostname(host->mmc), (int)mask);
> +               pr_err("%s: clean reset bit\n", mmc_hostname(host->mmc));

It looks silly to do two pr_err immediately after each other, please
combine them into one.

Moreover, I think we should probably convert into using a pr_warn() instead.

> +               sdhci_writeb(host, 0, SDHCI_UHS2_SW_RESET);
> +               return;
> +       }
> +}
> +EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
> +
>  /*****************************************************************************\
>   *                                                                           *
>   * Driver init/exit                                                          *
> diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
> index 2bfe18d29bca..8253d50f7852 100644
> --- a/drivers/mmc/host/sdhci-uhs2.h
> +++ b/drivers/mmc/host/sdhci-uhs2.h
> @@ -177,5 +177,7 @@
>  struct sdhci_host;
>
>  void sdhci_uhs2_dump_regs(struct sdhci_host *host);
> +bool sdhci_uhs2_mode(struct sdhci_host *host);
> +void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);
>
>  #endif /* __SDHCI_UHS2_H */
> --
> 2.25.1
>

Kind regards
Uffe