linux-kernel - Re: [PATCH v2 1/2] mmc: sdhci: add sdma_buffer_boundary_arg member to sdhci

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Date:   Thu, 3 Aug 2017 14:39:36 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     srinivas.kandagatla@...aro.org, ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mmc: sdhci: add sdma_buffer_boundary_arg member to
 sdhci_host

On 02/08/17 11:38, srinivas.kandagatla@...aro.org wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> 
> This patch adds sdma_buffer_boundary_arg member to struct sdhci_host to
> give more flexibility to drivers to control the sdma boundary buffer value
> and also to fix issue on some sdhci controllers which are broken when
> HOST SDMA Buffer Boundary is programmed in Block Size Register (0x04)
> when using ADMA. Qualcomm sdhci controller is one of such type, writing
> to this bits is un-supported.
> 
> Default value of sdma_buffer_boundary_arg is set to SDHCI_DEFAULT_BOUNDARY_ARG.
> 
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>

There are a couple of minor suggestions below

> ---
>  drivers/mmc/host/sdhci.c | 14 ++++++++++----
>  drivers/mmc/host/sdhci.h |  3 +++
>  2 files changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index ecd0d4350e8a..4a7b5dcfc55b 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -897,7 +897,7 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
>  	sdhci_set_transfer_irqs(host);
>  
>  	/* Set the DMA boundary value and block size */
> -	sdhci_writew(host, SDHCI_MAKE_BLKSZ(SDHCI_DEFAULT_BOUNDARY_ARG,
> +	sdhci_writew(host, SDHCI_MAKE_BLKSZ(host->sdma_buffer_boundary_arg,
>  		data->blksz), SDHCI_BLOCK_SIZE);
>  	sdhci_writew(host, data->blocks, SDHCI_BLOCK_COUNT);
>  }
> @@ -2037,6 +2037,7 @@ static void sdhci_send_tuning(struct sdhci_host *host, u32 opcode)
>  	struct mmc_command cmd = {};
>  	struct mmc_request mrq = {};
>  	unsigned long flags;
> +	u32 barg = host->sdma_buffer_boundary_arg;

Might as well use a 2-character variable name and avoid the line wrapping
e.g. 'barg' -> 'sb'

>  
>  	spin_lock_irqsave(&host->lock, flags);
>  
> @@ -2052,9 +2053,11 @@ static void sdhci_send_tuning(struct sdhci_host *host, u32 opcode)
>  	 */
>  	if (cmd.opcode == MMC_SEND_TUNING_BLOCK_HS200 &&
>  	    mmc->ios.bus_width == MMC_BUS_WIDTH_8)
> -		sdhci_writew(host, SDHCI_MAKE_BLKSZ(7, 128), SDHCI_BLOCK_SIZE);
> +		sdhci_writew(host,
> +			     SDHCI_MAKE_BLKSZ(barg, 128), SDHCI_BLOCK_SIZE);
>  	else
> -		sdhci_writew(host, SDHCI_MAKE_BLKSZ(7, 64), SDHCI_BLOCK_SIZE);
> +		sdhci_writew(host,
> +			     SDHCI_MAKE_BLKSZ(barg, 64), SDHCI_BLOCK_SIZE);
>  
>  	/*
>  	 * The tuning block is sent by the card to the host controller.
> @@ -2998,7 +3001,8 @@ void sdhci_cqe_enable(struct mmc_host *mmc)
>  		ctrl |= SDHCI_CTRL_ADMA32;
>  	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>  
> -	sdhci_writew(host, SDHCI_MAKE_BLKSZ(SDHCI_DEFAULT_BOUNDARY_ARG, 512),
> +	sdhci_writew(host,
> +		     SDHCI_MAKE_BLKSZ(host->sdma_buffer_boundary_arg, 512),
>  		     SDHCI_BLOCK_SIZE);
>  
>  	/* Set maximum timeout */
> @@ -3119,6 +3123,8 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
>  
>  	host->tuning_delay = -1;
>  
> +	host->sdma_buffer_boundary_arg = SDHCI_DEFAULT_BOUNDARY_ARG;
> +
>  	return host;
>  }
>  
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 0469fa191493..6ff2294e55b3 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -541,6 +541,9 @@ struct sdhci_host {
>  	/* Delay (ms) between tuning commands */
>  	int			tuning_delay;
>  
> +	/* Host SDMA buffer boundary. */
> +	u32			sdma_buffer_boundary_arg;

The name seems a bit long.  What about just 'sdma_boundary'?

> +
>  	unsigned long private[0] ____cacheline_aligned;
>  };
>  
>