linux-kernel - Re: [PATCH V12 13/23] mmc: sdhci-uhs2: add set

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Date:   Tue, 3 Oct 2023 12:54:43 +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 13/23] mmc: sdhci-uhs2: add set_timeout()

On Fri, 15 Sept 2023 at 11:44, Victor Shih <victorshihgli@...il.com> wrote:
>
> From: Victor Shih <victor.shih@...esyslogic.com.tw>
>
> This is a UHS-II version of sdhci's set_timeout() operation.

This needs more explanations and justifications.

Other than that, the patch looks good to me!

Kind regards
Uffe

>
> 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:
>  - Initialization be combined with declaration and realigned
>    in sdhci_calc_timeout_uhs2().
>  - Forward declare struct mmc_command in sdhci_uhs2.h.
>
> Updates in V6:
>  - Use GENMASK() and FIELD_PREP() in some case.
>  - Use sdhci_uhs2_mode() to simplify code.
>  - Remove unnecessary functions.
>
> ---
>
>  drivers/mmc/host/sdhci-uhs2.c | 72 +++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci-uhs2.h |  2 +
>  2 files changed, 74 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> index 92fb69b7e209..d519e6ce6199 100644
> --- a/drivers/mmc/host/sdhci-uhs2.c
> +++ b/drivers/mmc/host/sdhci-uhs2.c
> @@ -13,6 +13,7 @@
>  #include <linux/delay.h>
>  #include <linux/module.h>
>  #include <linux/iopoll.h>
> +#include <linux/bitfield.h>
>
>  #include "sdhci.h"
>  #include "sdhci-uhs2.h"
> @@ -142,6 +143,77 @@ static void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode, un
>         }
>  }
>
> +static u8 sdhci_calc_timeout_uhs2(struct sdhci_host *host, u8 *cmd_res, u8 *dead_lock)
> +{
> +       /* timeout in us */
> +       unsigned int dead_lock_timeout = 1 * 1000 * 1000;
> +       unsigned int cmd_res_timeout = 5 * 1000;
> +       unsigned int current_timeout;
> +       u8 count;
> +
> +       /*
> +        * Figure out needed cycles.
> +        * We do this in steps in order to fit inside a 32 bit int.
> +        * The first step is the minimum timeout, which will have a
> +        * minimum resolution of 6 bits:
> +        * (1) 2^13*1000 > 2^22,
> +        * (2) host->timeout_clk < 2^16
> +        *     =>
> +        *     (1) / (2) > 2^6
> +        */
> +       count = 0;
> +       current_timeout = (1 << 13) * 1000 / host->timeout_clk;
> +       while (current_timeout < cmd_res_timeout) {
> +               count++;
> +               current_timeout <<= 1;
> +               if (count >= 0xF)
> +                       break;
> +       }
> +
> +       if (count >= 0xF) {
> +               DBG("%s: Too large timeout 0x%x requested for CMD_RES!\n",
> +                   mmc_hostname(host->mmc), count);
> +               count = 0xE;
> +       }
> +       *cmd_res = count;
> +
> +       count = 0;
> +       current_timeout = (1 << 13) * 1000 / host->timeout_clk;
> +       while (current_timeout < dead_lock_timeout) {
> +               count++;
> +               current_timeout <<= 1;
> +               if (count >= 0xF)
> +                       break;
> +       }
> +
> +       if (count >= 0xF) {
> +               DBG("%s: Too large timeout 0x%x requested for DEADLOCK!\n",
> +                   mmc_hostname(host->mmc), count);
> +               count = 0xE;
> +       }
> +       *dead_lock = count;
> +
> +       return count;
> +}
> +
> +static void __sdhci_uhs2_set_timeout(struct sdhci_host *host)
> +{
> +       u8 cmd_res, dead_lock;
> +
> +       sdhci_calc_timeout_uhs2(host, &cmd_res, &dead_lock);
> +       cmd_res |= FIELD_PREP(SDHCI_UHS2_TIMER_CTRL_DEADLOCK_MASK, dead_lock);
> +       sdhci_writeb(host, cmd_res, SDHCI_UHS2_TIMER_CTRL);
> +}
> +
> +void sdhci_uhs2_set_timeout(struct sdhci_host *host, struct mmc_command *cmd)
> +{
> +       __sdhci_set_timeout(host, cmd);
> +
> +       if (sdhci_uhs2_mode(host))
> +               __sdhci_uhs2_set_timeout(host);
> +}
> +EXPORT_SYMBOL_GPL(sdhci_uhs2_set_timeout);
> +
>  /*****************************************************************************\
>   *                                                                           *
>   * MMC callbacks                                                             *
> diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
> index 8253d50f7852..ccf4e1834c2d 100644
> --- a/drivers/mmc/host/sdhci-uhs2.h
> +++ b/drivers/mmc/host/sdhci-uhs2.h
> @@ -175,9 +175,11 @@
>  #define SDHCI_UHS2_VENDOR_PTR                  0xE8
>
>  struct sdhci_host;
> +struct mmc_command;
>
>  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);
> +void sdhci_uhs2_set_timeout(struct sdhci_host *host, struct mmc_command *cmd);
>
>  #endif /* __SDHCI_UHS2_H */
> --
> 2.25.1
>