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Message-ID: <69dd8714-4be1-6b1b-fa07-04c790a6c6fc@intel.com>
Date: Fri, 9 Dec 2022 14:13:06 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Vadym Kochan <vadym.kochan@...ision.eu>,
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
On 9/12/22 14:10, Vadym Kochan wrote:
> 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
Right but I guess I meant what about 0x3_00000000..0x3_ffffffff ?
Isn't that also in DMA_BIT_MASK(34)
>
>>>
>>>>>
>>>>> 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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