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Date: Fri, 09 Dec 2022 14:10:46 +0200
From: Vadym Kochan <vadym.kochan@...ision.eu>
To: Adrian Hunter <adrian.hunter@...el.com>,
Hu Ziji <huziji@...vell.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Elad Nachman <enachman@...vell.com>,
Chris Packham <chris.packham@...iedtelesis.co.nz>
Subject: Re: [PATCH v3 3/3] mmc: xenon: Fix 2G limitation on AC5 SoC
Hi Adrian,
On Fri, 9 Dec 2022 13:53:58 +0200, Adrian Hunter <adrian.hunter@...el.com> wrote:
> On 9/12/22 13:39, Vadym Kochan wrote:
> > Hi Adrian,
> >
> > On Fri, 9 Dec 2022 09:23:05 +0200, Adrian Hunter <adrian.hunter@...el.com> wrote:
> >> On 5/12/22 12:59, Vadym Kochan wrote:
> >>> There is a limitation on AC5 SoC that mmc controller
> >>> can't have DMA access over 2G memory, so use SDMA with
> >>> a bounce buffer. Swiotlb can't help because on arm64 arch
> >>> it reserves memblock's at the end of the memory.
> >>>
> >>> Additionally set mask to 34 bit since on AC5 SoC RAM starts
> >>> at 0x2_00000000.
> >>
> >> Can you explain more about how a 34-bit DMA mask works when
> >> SDMA only supports 32-bit addresses?
> >>
> >
> > So, after I set
> >
> >>> + host->flags &= ~SDHCI_USE_64_BIT_DMA;
> >
> > then sdhc core sets mask to 32 bit, but then dma_map fails to map
> > bounce buffer because the base address is higher than 32bit - 0x2_00000000,
> > and 34bit mask fixed it.
>
> What happens if the bounce buffer gets mapped in the range
> 0x1_00000000 to 0x1_ffffffff ?
>
>From my understanding, on the AC5 SoC RAM starts at 0x2_00000000 so the bounce
buffer can be mapped in the range 0x2_00000000..0x2_ffffffff
> >
> >>>
> >>> Co-developed-by: Elad Nachman <enachman@...vell.com>
> >>> Signed-off-by: Elad Nachman <enachman@...vell.com>
> >>> Signed-off-by: Vadym Kochan <vadym.kochan@...ision.eu>
> >>> ---
> >>> drivers/mmc/host/sdhci-xenon.c | 38 ++++++++++++++++++++++++++++++++++
> >>> drivers/mmc/host/sdhci-xenon.h | 3 ++-
> >>> 2 files changed, 40 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/mmc/host/sdhci-xenon.c b/drivers/mmc/host/sdhci-xenon.c
> >>> index 08e838400b52..5f3db0425674 100644
> >>> --- a/drivers/mmc/host/sdhci-xenon.c
> >>> +++ b/drivers/mmc/host/sdhci-xenon.c
> >>> @@ -13,7 +13,9 @@
> >>>
> >>> #include <linux/acpi.h>
> >>> #include <linux/delay.h>
> >>> +#include <linux/dma-mapping.h>
> >>> #include <linux/ktime.h>
> >>> +#include <linux/mm.h>
> >>> #include <linux/module.h>
> >>> #include <linux/of.h>
> >>> #include <linux/pm.h>
> >>> @@ -253,6 +255,22 @@ static unsigned int xenon_get_max_clock(struct sdhci_host *host)
> >>> return pltfm_host->clock;
> >>> }
> >>>
> >>> +static int xenon_set_dma_mask(struct sdhci_host *host)
> >>> +{
> >>> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> >>> + struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
> >>> + struct mmc_host *mmc = host->mmc;
> >>> + struct device *dev = mmc_dev(mmc);
> >>> +
> >>> + if (priv->hw_version == XENON_AC5) {
> >>> + host->flags &= ~SDHCI_USE_64_BIT_DMA;
> >>> +
> >>> + return dma_set_mask_and_coherent(dev, DMA_BIT_MASK(34));
> >>> + }
> >>> +
> >>> + return sdhci_set_dma_mask(host);
> >>> +}
> >>> +
> >>> static const struct sdhci_ops sdhci_xenon_ops = {
> >>> .voltage_switch = xenon_voltage_switch,
> >>> .set_clock = sdhci_set_clock,
> >>> @@ -261,6 +279,7 @@ static const struct sdhci_ops sdhci_xenon_ops = {
> >>> .reset = xenon_reset,
> >>> .set_uhs_signaling = xenon_set_uhs_signaling,
> >>> .get_max_clock = xenon_get_max_clock,
> >>> + .set_dma_mask = xenon_set_dma_mask,
> >>> };
> >>>
> >>> static const struct sdhci_pltfm_data sdhci_xenon_pdata = {
> >>> @@ -486,6 +505,18 @@ static void xenon_sdhc_unprepare(struct sdhci_host *host)
> >>> xenon_disable_sdhc(host, sdhc_id);
> >>> }
> >>>
> >>> +static int xenon_ac5_probe(struct sdhci_host *host)
> >>> +{
> >>> + struct sysinfo si;
> >>> +
> >>> + si_meminfo(&si);
> >>> +
> >>> + if ((si.totalram * si.mem_unit) > SZ_2G)
> >>> + host->quirks |= SDHCI_QUIRK_BROKEN_ADMA;
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> static int xenon_probe(struct platform_device *pdev)
> >>> {
> >>> struct sdhci_pltfm_host *pltfm_host;
> >>> @@ -533,6 +564,12 @@ static int xenon_probe(struct platform_device *pdev)
> >>> }
> >>> }
> >>>
> >>> + if (priv->hw_version == XENON_AC5) {
> >>> + err = xenon_ac5_probe(host);
> >>> + if (err)
> >>> + goto err_clk_axi;
> >>> + }
> >>> +
> >>> err = mmc_of_parse(host->mmc);
> >>> if (err)
> >>> goto err_clk_axi;
> >>> @@ -682,6 +719,7 @@ 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 {
> >>
> >
> > Regards,
>
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