linux-kernel - Re: [PATCH V7 7/9] mmc: sdhci: SDMA may use Auto-CMD23 in v4 mode

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Message-ID: <CAAfSe-tKKiV0CCN2Oz6wY5XmfO2aAJHPBcaP48YiEji=PUV5sw@mail.gmail.com>
Date:   Thu, 30 Aug 2018 16:23:03 +0800
From:   Chunyan Zhang <zhang.lyra@...il.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Chunyan Zhang <zhang.chunyan@...aro.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-mmc@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...aro.org>,
        Billows Wu <billows.wu@...soc.com>,
        Jason Wu <jason.wu@...soc.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>
Subject: Re: [PATCH V7 7/9] mmc: sdhci: SDMA may use Auto-CMD23 in v4 mode

On 30 August 2018 at 15:51, Adrian Hunter <adrian.hunter@...el.com> wrote:
> On 30/08/18 10:04, Chunyan Zhang wrote:
>> On 30 August 2018 at 13:59, Adrian Hunter <adrian.hunter@...el.com> wrote:
>>> On 29/08/18 14:39, Chunyan Zhang wrote:
>>>> On 29 August 2018 at 18:59, Adrian Hunter <adrian.hunter@...el.com> wrote:
>>>>> On 29/08/18 10:03, Chunyan Zhang wrote:
>>>>>> When Host Version 4 Enable is set to 1, SDMA uses ADMA System Address
>>>>>> register (05Fh-058h) instead of using register (000h-004h) to indicate
>>>>>> its system address of data location. The register (000h-004h) is
>>>>>> re-assigned to 32-bit Block Count and Auto CMD23 argument, so then SDMA
>>>>>> may use Auto CMD23.
>>>>>>
>>>>>> Signed-off-by: Chunyan Zhang <zhang.chunyan@...aro.org>
>>>>>> ---
>>>>>>  drivers/mmc/host/sdhci.c | 8 ++++++--
>>>>>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>>>> index 62d843ac90..ac92e0f 100644
>>>>>> --- a/drivers/mmc/host/sdhci.c
>>>>>> +++ b/drivers/mmc/host/sdhci.c
>>>>>> @@ -3834,10 +3834,14 @@ int sdhci_setup_host(struct sdhci_host *host)
>>>>>>       if (host->quirks & SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12)
>>>>>>               host->flags |= SDHCI_AUTO_CMD12;
>>>>>>
>>>>>> -     /* Auto-CMD23 stuff only works in ADMA or PIO. */
>>>>>> +     /*
>>>>>> +      * For v3 mode, Auto-CMD23 stuff only works in ADMA or PIO;
>>>>>
>>>>> ; -> .
>>>>>
>>>>>> +      * For v4 mode, SDMA may use Auto-CMD23 as well.
>>>>>> +      */
>>>>>>       if ((host->version >= SDHCI_SPEC_300) &&
>>>>>>           ((host->flags & SDHCI_USE_ADMA) ||
>>>>>> -          !(host->flags & SDHCI_USE_SDMA)) &&
>>>>>> +          (!host->v4_mode && !(host->flags & SDHCI_USE_SDMA)) ||
>>>>>> +          (host->v4_mode && (host->flags & SDHCI_USE_SDMA))) &&
>>>>>>            !(host->quirks2 & SDHCI_QUIRK2_ACMD23_BROKEN)) {
>>>>>
>>>>> This is over complicated.  We can use auto-CMD23 if not using SDMA or if in
>>>>> v4_mode i.e.
>>>>>
>>>>>         if (host->version >= SDHCI_SPEC_300 &&
>>>>>             (!(host->flags & SDHCI_USE_SDMA) || host->v4_mode) &&
>>>>>             !(host->quirks2 & SDHCI_QUIRK2_ACMD23_BROKEN)) {
>>>>>
>>>>
>>>> So no matter whether SDHCI_USE_ADMA is selected, right?
>>>
>>> Yes
>>
>> I think you mean like this:
>>
>> if ((host->version >= SDHCI_SPEC_300) &&
>>     ((host->flags & SDHCI_USE_ADMA) ||
>>      !(host->flags & SDHCI_USE_SDMA) || host->v4_mode) &&
>>      !(host->quirks2 & SDHCI_QUIRK2_ACMD23_BROKEN))
>>
>> Otherwise, without checking (host->flags & SDHCI_USE_ADMA), if using
>> ADMA and SDMA on v3 mode, auto-CMD23 would not be selected.
>
> Yeah you are right - I was thinking SDHCI_USE_SDMA and SDHCI_USE_ADMA were
> mutually exclusive.  Thanks!

Many thanks for your review!

Chunyan

>