linux-kernel - Re: [PATCH v2] mmc: xenon: Add ac5 support via bounce buffer

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Message-ID: <CAPDyKFoJffGOu1cBeUi=Lg5u+MNxg6Xbp5qpjisHWM5oxXW6BA@mail.gmail.com>
Date: Fri, 5 Jan 2024 11:18:53 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Elad Nachman <enachman@...vell.com>
Cc: huziji@...vell.com, adrian.hunter@...el.com, linux-mmc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mmc: xenon: Add ac5 support via bounce buffer

On Thu, 4 Jan 2024 at 18:31, Elad Nachman <enachman@...vell.com> wrote:
>
> From: Elad Nachman <enachman@...vell.com>
>
> AC5/X/IM SOCs has a variant of the Xenon eMMC controller,
> in which only 31-bit of addressing pass from the controller
> on the AXI bus.
> Since we cannot guarantee that only buffers from the first 2GB
> of memory will reach the driver, the driver is configured for
> SDMA mode, without 64-bit mode, overriding the DMA mask to 34-bit
> to support the DDR memory mapping, which starts at offset 8GB.
>
> Signed-off-by: Elad Nachman <enachman@...vell.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/sdhci-xenon.c | 31 +++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci-xenon.h |  3 ++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-xenon.c b/drivers/mmc/host/sdhci-xenon.c
> index 25ba7aecc3be..0e52867f6e91 100644
> --- a/drivers/mmc/host/sdhci-xenon.c
> +++ b/drivers/mmc/host/sdhci-xenon.c
> @@ -18,6 +18,8 @@
>  #include <linux/of.h>
>  #include <linux/pm.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/mm.h>
> +#include <linux/dma-mapping.h>
>
>  #include "sdhci-pltfm.h"
>  #include "sdhci-xenon.h"
> @@ -422,6 +424,7 @@ static int xenon_probe_params(struct platform_device *pdev)
>         struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
>         u32 sdhc_id, nr_sdhc;
>         u32 tuning_count;
> +       struct sysinfo si;
>
>         /* Disable HS200 on Armada AP806 */
>         if (priv->hw_version == XENON_AP806)
> @@ -450,6 +453,23 @@ static int xenon_probe_params(struct platform_device *pdev)
>         }
>         priv->tuning_count = tuning_count;
>
> +       /*
> +        * AC5/X/IM HW has only 31-bits passed in the crossbar switch.
> +        * If we have more than 2GB of memory, this means we might pass
> +        * memory pointers which are above 2GB and which cannot be properly
> +        * represented. In this case, disable ADMA, 64-bit DMA and allow only SDMA.
> +        * This effectively will enable bounce buffer quirk in the
> +        * generic SDHCI driver, which will make sure DMA is only done
> +        * from supported memory regions:
> +        */
> +       if (priv->hw_version == XENON_AC5) {
> +               si_meminfo(&si);
> +               if (si.totalram * si.mem_unit > SZ_2G) {
> +                       host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> +                       host->quirks2 |= SDHCI_QUIRK2_BROKEN_64_BIT_DMA;
> +               }
> +       }
> +
>         return xenon_phy_parse_params(dev, host);
>  }
>
> @@ -562,6 +582,16 @@ static int xenon_probe(struct platform_device *pdev)
>                 goto remove_sdhc;
>
>         pm_runtime_put_autosuspend(&pdev->dev);
> +       /*
> +        * If we previously detected AC5 with over 2GB of memory,
> +        * then we disable ADMA and 64-bit DMA.
> +        * This means generic SDHCI driver has set the DMA mask to
> +        * 32-bit. Since DDR starts at 0x2_0000_0000, we must use
> +        * 34-bit DMA mask to access this DDR memory:
> +        */
> +       if (priv->hw_version == XENON_AC5 &&
> +           host->quirks2 & SDHCI_QUIRK2_BROKEN_64_BIT_DMA)
> +               dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(34));
>
>         return 0;
>
> @@ -680,6 +710,7 @@ static const struct of_device_id sdhci_xenon_dt_ids[] = {
>         { .compatible = "marvell,armada-ap807-sdhci", .data = (void *)XENON_AP807},
>         { .compatible = "marvell,armada-cp110-sdhci", .data =  (void *)XENON_CP110},
>         { .compatible = "marvell,armada-3700-sdhci", .data =  (void *)XENON_A3700},
> +       { .compatible = "marvell,ac5-sdhci",         .data =  (void *)XENON_AC5},
>         {}
>  };
>  MODULE_DEVICE_TABLE(of, sdhci_xenon_dt_ids);
> diff --git a/drivers/mmc/host/sdhci-xenon.h b/drivers/mmc/host/sdhci-xenon.h
> index 3e9c6c908a79..0460d97aad26 100644
> --- a/drivers/mmc/host/sdhci-xenon.h
> +++ b/drivers/mmc/host/sdhci-xenon.h
> @@ -57,7 +57,8 @@ enum xenon_variant {
>         XENON_A3700,
>         XENON_AP806,
>         XENON_AP807,
> -       XENON_CP110
> +       XENON_CP110,
> +       XENON_AC5
>  };
>
>  struct xenon_priv {
> --
> 2.25.1
>