From: Adrian Hunter <adrian.hunter@intel.com>
To: Jisheng Zhang <Jisheng.Zhang@synaptics.com>,
Ulf Hansson <ulf.hansson@linaro.org>
Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation
Date: Tue, 28 Aug 2018 13:47:12 +0300 [thread overview]
Message-ID: <6f1f9655-7fe4-a25c-c981-5027fa444334@intel.com> (raw)
In-Reply-To: <20180828174814.40dfa48f@xhacker.debian>
On 28/08/18 12:48, Jisheng Zhang wrote:
> When using DMA, if the DMA addr spans 128MB boundary, we have to split
> the DMA transfer into two so that each one doesn't exceed the boundary.
>
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +++++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index 1b7cd144fb01..a5137845a1c7 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -8,21 +8,51 @@
> */
>
> #include <linux/clk.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/sizes.h>
>
> #include "sdhci-pltfm.h"
>
> +#define BOUNDARY_OK(addr, len) \
> + ((addr | (SZ_128M - 1)) == ((addr + len - 1) | (SZ_128M - 1)))
> +
> struct dwcmshc_priv {
> struct clk *bus_clk;
> };
>
> +/*
> + * If DMA addr spans 128MB boundary, we split the DMA transfer into two
> + * so that each DMA transfer doesn't exceed the boundary.
> + */
> +static void dwcmshc_adma_write_desc(struct sdhci_host *host, void **desc,
> + dma_addr_t addr, int len, unsigned int cmd)
> +{
> + int tmplen, offset;
> +
> + if (likely(!len || BOUNDARY_OK(addr, len))) {
> + sdhci_adma_write_desc(host, desc, addr, len, cmd);
> + return;
> + }
> +
> + offset = addr & (SZ_128M - 1);
> + tmplen = SZ_128M - offset;
> + sdhci_adma_write_desc(host, desc, addr, tmplen, cmd);
> +
> + addr += tmplen;
> + len -= tmplen;
> + sdhci_adma_write_desc(host, desc, addr, len, cmd);
> +}
> +
> static const struct sdhci_ops sdhci_dwcmshc_ops = {
> .set_clock = sdhci_set_clock,
> .set_bus_width = sdhci_set_bus_width,
> .set_uhs_signaling = sdhci_set_uhs_signaling,
> .get_max_clock = sdhci_pltfm_clk_get_max_clock,
> .reset = sdhci_reset,
> + .adma_write_desc = dwcmshc_adma_write_desc,
> };
>
> static const struct sdhci_pltfm_data sdhci_dwcmshc_pdata = {
> @@ -36,12 +66,21 @@ static int dwcmshc_probe(struct platform_device *pdev)
> struct sdhci_host *host;
> struct dwcmshc_priv *priv;
> int err;
> + u32 extra;
>
> host = sdhci_pltfm_init(pdev, &sdhci_dwcmshc_pdata,
> sizeof(struct dwcmshc_priv));
> if (IS_ERR(host))
> return PTR_ERR(host);
>
> + /*
> + * extra adma table cnt for cross 128M boundary handling.
> + */
> + extra = DIV_ROUND_UP_ULL(dma_get_required_mask(&pdev->dev), SZ_128M);
> + if (extra > SDHCI_MAX_SEGS)
> + extra = SDHCI_MAX_SEGS;
> + host->adma_table_cnt += extra;
> +
> pltfm_host = sdhci_priv(host);
> priv = sdhci_pltfm_priv(pltfm_host);
>
>
next prev parent reply other threads:[~2018-08-28 10:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-28 9:45 [PATCH v6 0/3] solve SDHCI DWC MSHC 128MB DMA boundary limitation Jisheng Zhang
2018-08-28 9:46 ` [PATCH v6 1/3] mmc: sdhci: add adma_table_cnt member to struct sdhci_host Jisheng Zhang
2018-08-28 9:47 ` [PATCH v6 2/3] mmc: sdhci: introduce adma_write_desc() hook to struct sdhci_ops Jisheng Zhang
2018-08-28 9:48 ` [PATCH v6 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation Jisheng Zhang
2018-08-28 10:47 ` Adrian Hunter [this message]
2018-08-28 11:41 ` [PATCH v6 0/3] solve SDHCI DWC MSHC " Ulf Hansson
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