Re: [RFC PATCH] mmc: block: Support the fixed index for mmcblk with aliases nodes

[Jisheng Zhang <jszhang@marvell.com>]

Hi Jaehoon,

On Tue, 29 Mar 2016 19:43:34 +0900 Jaehoon Chung wrote:

> This patch is just RFC. I want to know opinions.
> 
> Now, index of mmcblk is allocated in accordance with probing time.
> If want to use the mmcblk1 for some device, it can use alias.
> 
> aliases {
> 	mmc0 = &mmc0;	/* mmcblk0 for eMMC */
> 	mmc1 = &mmc2;	/* mmcblk1 for SD */
> 	mmc2 = &mmc1;	/* mmcblk2 for SDIO*/
> };

I like this feature and we do need it. In the past, we have to put emmc dt node
before the sd node, but on our platform, the register base of sdhc host for emmc
is higher than the one for sd, putting emmc dt node before sd looks a bit
strange, but we have no better solutions.

Thanks,
Jisheng

> 
> If there are no corresponding values, it might be allocated with
> existing scheme.
> 
> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
> ---
>  Documentation/devicetree/bindings/mmc/mmc.txt | 11 +++++++++++
>  drivers/mmc/card/block.c                      | 17 ++++++++++++++++-
>  2 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
> index ed23b9b..e37ea29 100644
> --- a/Documentation/devicetree/bindings/mmc/mmc.txt
> +++ b/Documentation/devicetree/bindings/mmc/mmc.txt
> @@ -71,6 +71,10 @@ Optional SDIO properties:
>  - wakeup-source: Enables wake up of host system on SDIO IRQ assertion
>  		 (Legacy property supported: "enable-sdio-wakeup")
>  
> +Aliases (Optional):
> +- If you want to use the fixed index for block device like mmcblkX, should be
> +represented in the aliases node using following format "mmc(X)".
> +(X is an unique number for the alias.)
>  
>  MMC power sequences:
>  --------------------
> @@ -145,3 +149,10 @@ mmc3: mmc@01c12000 {
>  		interrupt-names = "host-wake";
>  	};
>  };
> +
> +Example with aliases nodes:
> +
> +aliases {
> +	mmc0 = &mmc0;	/* Fixed to mmcblk0 for &mmc0 */
> +	mmc1 = &mmc2;	/* Fixed to mmcblk1 for &mmc2 */
> +};
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 3bdbe50..6a40de5 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -35,6 +35,7 @@
>  #include <linux/capability.h>
>  #include <linux/compat.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/of.h>
>  
>  #include <linux/mmc/ioctl.h>
>  #include <linux/mmc/card.h>
> @@ -2190,6 +2191,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
>  {
>  	struct mmc_blk_data *md;
>  	int devidx, ret;
> +	int idx = 0;
>  
>  	devidx = find_first_zero_bit(dev_use, max_devices);
>  	if (devidx >= max_devices)
> @@ -2209,7 +2211,20 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
>  	 * index anymore so we keep track of a name index.
>  	 */
>  	if (!subname) {
> -		md->name_idx = find_first_zero_bit(name_use, max_devices);
> +		if (card->dev.parent->parent->of_node)
> +			idx = of_alias_get_id(card->dev.parent->parent->of_node,
> +					"mmc");
> +
> +		if (idx < 0)
> +			md->name_idx = find_first_zero_bit(name_use,
> +					max_devices);
> +		else {
> +			if (test_bit(idx, name_use))
> +				md->name_idx = find_first_zero_bit(name_use,
> +						max_devices);
> +			else
> +				md->name_idx = (unsigned int)idx;
> +		}
>  		__set_bit(md->name_idx, name_use);
>  	} else
>  		md->name_idx = ((struct mmc_blk_data *)