linux-kernel - Re: [PATCH] mmc: sdhci-cadence: fix PHY write

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Date:   Thu, 28 May 2020 12:14:04 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Vladimir Kondratiev <vladimir.kondratiev@...el.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: sdhci-cadence: fix PHY write

On Mon, 25 May 2020 at 09:41, Vladimir Kondratiev
<vladimir.kondratiev@...el.com> wrote:
>
> Accordingly to Cadence documentation, PHY write procedure is:
>
> 1. Software sets the PHY Register Address (HRS04[5:0]) and the
>    PHY Write Data (HRS04[15:8]) fields.
> 2. Software sets the PHY Write Transaction Request (HRS04[24]) field to 1.
> 3. Software waits as the PHY Write Transaction Acknowledge (HRS04[26])
>    field is equal to 0.
> 4. Hardware performs the write transaction to PHY register where
>    HRS04[15:8] is a data written to register under HRS04[5:0] address.
> 5. Hardware sets the PHY Transaction Acknowledge (HRS04[26]) to 1 when
>    transaction is completed.
> 6. Software clears the PHY Write Transaction Request (HRS04[24]) to 1
>    after noticing that the PHY Write Transaction Acknowledge (HRS04[26])
>    field is equal to 1.
> 7. Software waits for the PHY Acknowledge Register (HRS04[26]) field is
>    equal to 0.
>
> Add missing steps 3 and 7. Lack of these steps causes
> integrity errors detested by hardware.
>
> Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@...el.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/sdhci-cadence.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
> index e474d3fa099e..6b2e7c43cbc1 100644
> --- a/drivers/mmc/host/sdhci-cadence.c
> +++ b/drivers/mmc/host/sdhci-cadence.c
> @@ -114,6 +114,11 @@ static int sdhci_cdns_write_phy_reg(struct sdhci_cdns_priv *priv,
>         u32 tmp;
>         int ret;
>
> +       ret = readl_poll_timeout(reg, tmp, !(tmp & SDHCI_CDNS_HRS04_ACK),
> +                                0, 10);
> +       if (ret)
> +               return ret;
> +
>         tmp = FIELD_PREP(SDHCI_CDNS_HRS04_WDATA, data) |
>               FIELD_PREP(SDHCI_CDNS_HRS04_ADDR, addr);
>         writel(tmp, reg);
> @@ -128,7 +133,10 @@ static int sdhci_cdns_write_phy_reg(struct sdhci_cdns_priv *priv,
>         tmp &= ~SDHCI_CDNS_HRS04_WR;
>         writel(tmp, reg);
>
> -       return 0;
> +       ret = readl_poll_timeout(reg, tmp, !(tmp & SDHCI_CDNS_HRS04_ACK),
> +                                0, 10);
> +
> +       return ret;
>  }
>
>  static unsigned int sdhci_cdns_phy_param_count(struct device_node *np)
> --
> 2.20.1
>
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