Re: [PATCH v6] mmc: dw_mmc: Allow lower TMOUT value than maximum

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On 11/20/21 12:53 AM, Mårten Lindahl wrote:
> The TMOUT register is always set with a full value for every transfer,
> which (with a 200MHz clock) will give a full DRTO of ~84 milliseconds.
> This is normally good enough to complete the request, but setting a full
> value makes it impossible to test shorter timeouts, when for example
> testing data read times on different SD cards.
> 
> Add a function to set any value smaller than the maximum of 0xFFFFFF.
> 
> Signed-off-by: Mårten Lindahl <marten.lindahl@xxxxxxxx>

Reviewed-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>

Best Regards,
Jaehoon Chung

> ---
> 
> v2:
>  - Calculate new value before checking boundaries
>  - Include CLKDIV register to get proper value
> 
> v3:
>  - Use 'if-else' instead of 'goto'
>  - Don't touch response field when maximize data field
> 
> v4:
>  - Prevent 32bit divider overflow by splitting the operation
>  - Changed %06x to %#08x as suggested by Doug
>  - Rephrased commit msg as suggested by Doug
> 
> v5:
>  - Use u32 type for CPU reg access
>  - Make tmp 64bit to handle INT_MAX parameters
> 
> v6:
>  - Use u64 type for tmp
> 
>  drivers/mmc/host/dw_mmc.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index d977f34f6b55..f310d9438dff 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1283,6 +1283,33 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
>  	mci_writel(host, CTYPE, (slot->ctype << slot->id));
>  }
>  
> +static void dw_mci_set_data_timeout(struct dw_mci *host,
> +				    unsigned int timeout_ns)
> +{
> +	u32 clk_div, tmout;
> +	u64 tmp;
> +
> +	clk_div = (mci_readl(host, CLKDIV) & 0xFF) * 2;
> +	if (clk_div == 0)
> +		clk_div = 1;
> +
> +	tmp = DIV_ROUND_UP_ULL((u64)timeout_ns * host->bus_hz, NSEC_PER_SEC);
> +	tmp = DIV_ROUND_UP_ULL(tmp, clk_div);
> +
> +	/* TMOUT[7:0] (RESPONSE_TIMEOUT) */
> +	tmout = 0xFF; /* Set maximum */
> +
> +	/* TMOUT[31:8] (DATA_TIMEOUT) */
> +	if (!tmp || tmp > 0xFFFFFF)
> +		tmout |= (0xFFFFFF << 8);
> +	else
> +		tmout |= (tmp & 0xFFFFFF) << 8;
> +
> +	mci_writel(host, TMOUT, tmout);
> +	dev_dbg(host->dev, "timeout_ns: %u => TMOUT[31:8]: 0x%#08x",
> +		timeout_ns, tmout >> 8);
> +}
> +
>  static void __dw_mci_start_request(struct dw_mci *host,
>  				   struct dw_mci_slot *slot,
>  				   struct mmc_command *cmd)
> @@ -1303,7 +1330,7 @@ static void __dw_mci_start_request(struct dw_mci *host,
>  
>  	data = cmd->data;
>  	if (data) {
> -		mci_writel(host, TMOUT, 0xFFFFFFFF);
> +		dw_mci_set_data_timeout(host, data->timeout_ns);
>  		mci_writel(host, BYTCNT, data->blksz*data->blocks);
>  		mci_writel(host, BLKSIZ, data->blksz);
>  	}
> 




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