linux-kernel - Re: [PATCH V10 3/4] mmc: sdhci: Add ADMA3 DMA support for V4 enabled host

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Date:   Wed, 23 Jan 2019 09:27:38 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>, robh+dt@...nel.org,
        mark.rutland@....com, mperttunen@...dia.com,
        chunyan.zhang@...soc.com, thierry.reding@...il.com,
        jonathanh@...dia.com, ulf.hansson@...aro.org
Cc:     anrao@...dia.com, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Subject: Re: [PATCH V10 3/4] mmc: sdhci: Add ADMA3 DMA support for V4 enabled
 host

On 22/01/19 9:56 PM, Sowjanya Komatineni wrote:
> Below are the supported DMA types in Host Control1 Register
> with Version 4 enable
> b'00 - SDMA
> b'01 - Not Used
> b'10 - ADMA2
> b'11 - ADMA2 or ADMA3
> 
> ADMA3 uses Command Descriptor to issue an SD command.
> A multi-block data transfer is performed by using a pair of CMD
> descriptor and ADMA2 descriptor.
> 
> ADMA3 performs multiple of multi-block data transfer by using
> Integrated Descriptor which is more suitable for Command Queuing
> to fetch both Command and Transfer descriptors.
> 
> Host Capabilities register indiactes the supports of ADMA3 DMA.

indiactes -> indicates

> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
>  [V10]: Changes are same as V9 except this series has SDHCI core changes
> 	into seperate patch 
> 
>  drivers/mmc/host/sdhci.c | 9 ++++++++-
>  drivers/mmc/host/sdhci.h | 2 ++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index a22e11a65658..c6afe793399e 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3353,7 +3353,14 @@ void sdhci_cqe_enable(struct mmc_host *mmc)
>  
>  	ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
>  	ctrl &= ~SDHCI_CTRL_DMA_MASK;
> -	if (host->flags & SDHCI_USE_64_BIT_DMA)
> +	/*
> +	 * Host from V4.10 supports ADMA3 DMA type.
> +	 * ADMA3 performs integrated descriptor which is more suitable
> +	 * for cmd queuing to fetch both command and transfer descriptors.
> +	 */
> +	if (host->v4_mode && (host->caps1 & SDHCI_CAN_DO_ADMA3))
> +		ctrl |= SDHCI_CTRL_ADMA3;
> +	else if (host->flags & SDHCI_USE_64_BIT_DMA)
>  		ctrl |= SDHCI_CTRL_ADMA64;
>  	else
>  		ctrl |= SDHCI_CTRL_ADMA32;
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 6cc9a3c2ac66..4070be49d947 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -88,6 +88,7 @@
>  #define   SDHCI_CTRL_ADMA1	0x08
>  #define   SDHCI_CTRL_ADMA32	0x10
>  #define   SDHCI_CTRL_ADMA64	0x18
> +#define   SDHCI_CTRL_ADMA3	0x18
>  #define   SDHCI_CTRL_8BITBUS	0x20
>  #define  SDHCI_CTRL_CDTEST_INS	0x40
>  #define  SDHCI_CTRL_CDTEST_EN	0x80
> @@ -230,6 +231,7 @@
>  #define  SDHCI_RETUNING_MODE_SHIFT		14
>  #define  SDHCI_CLOCK_MUL_MASK	0x00FF0000
>  #define  SDHCI_CLOCK_MUL_SHIFT	16
> +#define  SDHCI_CAN_DO_ADMA3	0x08000000
>  #define  SDHCI_SUPPORT_HS400	0x80000000 /* Non-standard */
>  
>  #define SDHCI_CAPABILITIES_1	0x44
>