linux-kernel - Re: [PATCH] mmc: mmci: stm32: set feedback clock when using delay block

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Date:   Wed, 14 Jun 2023 12:31:27 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Yann Gautier <yann.gautier@...s.st.com>
Cc:     linux-mmc@...r.kernel.org, Philipp Zabel <p.zabel@...gutronix.de>,
        Christophe Kerello <christophe.kerello@...s.st.com>,
        linux-kernel@...r.kernel.org, Marek Vasut <marex@...x.de>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] mmc: mmci: stm32: set feedback clock when using delay block

On Tue, 13 Jun 2023 at 17:02, Yann Gautier <yann.gautier@...s.st.com> wrote:
>
> The feedback clock is used only for SDR104 & HS200 modes, and when
> delay block is used (frequency is higher than 50 MHz). The tuning
> procedure is then only required for those modes. Skip the procedure
> for other modes.
> The setting of this feedback clock is done just after enabling delay
> block, and before configuring it.
>
> Signed-off-by: Yann Gautier <yann.gautier@...s.st.com>
> Signed-off-by: Christophe Kerello <christophe.kerello@...s.st.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/mmci_stm32_sdmmc.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
> index 60bca78a72b19..953d1be4e379c 100644
> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
> @@ -293,18 +293,8 @@ static void mmci_sdmmc_set_clkreg(struct mmci_host *host, unsigned int desired)
>         clk |= host->clk_reg_add;
>         clk |= ddr;
>
> -       /*
> -        * SDMMC_FBCK is selected when an external Delay Block is needed
> -        * with SDR104 or HS200.
> -        */
> -       if (host->mmc->ios.timing >= MMC_TIMING_UHS_SDR50) {
> +       if (host->mmc->ios.timing >= MMC_TIMING_UHS_SDR50)
>                 clk |= MCI_STM32_CLK_BUSSPEED;
> -               if (host->mmc->ios.timing == MMC_TIMING_UHS_SDR104 ||
> -                   host->mmc->ios.timing == MMC_TIMING_MMC_HS200) {
> -                       clk &= ~MCI_STM32_CLK_SEL_MSK;
> -                       clk |= MCI_STM32_CLK_SELFBCK;
> -               }
> -       }
>
>         mmci_write_clkreg(host, clk);
>  }
> @@ -511,10 +501,27 @@ static int sdmmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
>  {
>         struct mmci_host *host = mmc_priv(mmc);
>         struct sdmmc_dlyb *dlyb = host->variant_priv;
> +       u32 clk;
> +
> +       if ((host->mmc->ios.timing != MMC_TIMING_UHS_SDR104 &&
> +            host->mmc->ios.timing != MMC_TIMING_MMC_HS200) ||
> +           host->mmc->actual_clock <= 50000000)
> +               return 0;
>
>         if (!dlyb || !dlyb->base)
>                 return -EINVAL;
>
> +       writel_relaxed(DLYB_CR_DEN, dlyb->base + DLYB_CR);
> +
> +       /*
> +        * SDMMC_FBCK is selected when an external Delay Block is needed
> +        * with SDR104 or HS200.
> +        */
> +       clk = host->clk_reg;
> +       clk &= ~MCI_STM32_CLK_SEL_MSK;
> +       clk |= MCI_STM32_CLK_SELFBCK;
> +       mmci_write_clkreg(host, clk);
> +
>         if (sdmmc_dlyb_lng_tuning(host))
>                 return -EINVAL;
>
> --
> 2.25.1
>