+Nishanth,
On Tuesday 13 October 2015 10:59 AM, Heiko Schocher wrote:
> On embedded devices, often there is a combination of
> removable mmc devices (e.g. MMC/SD cards) and hard
> wired ones (e.g. eMMC). Depending on the hardware
> configuration, the 'mmcblkN' node might change if
> the removable device is available or not at boot time.
>
> E.g. if the removable device is attached at boot time,
> it might become mmxblk0. And the hard wired one mmcblk1.
> But if the removable device isn't there at boot time,
> the hard wired one will become mmcblk0. This makes it
> somehow difficult to hard code the root device to the
> non-removable device and boot fast.
Why not use "root=PARTUUID=${uuid}" option instead of relying on mmcblk no?
U-Boot can easily detect your partuuid. Refer to [1] on how TI platforms
does this in u-boot.
[1]
http://git.denx.de/?p=u-boot.git;a=commitdiff;h=437bc42e7ff930dc4d4bd47199d2e823cf84bf4c;hp=85d17be374678ec37fd1e55db994a942e400dc80
Thanks and regards,
Lokesh
>
> Signed-off-by: Heiko Schocher <hs@xxxxxxx>
> ---
> Dirk Behme tried to bring this in, last mail I found:
> http://lists.infradead.org/pipermail/linux-arm-kernel/2012-July/111022.html
> where Dirk worked in Arnds suggestion to use the
> "/aliases" device node"
>
> I adapt this to the omap_hsmmc driver.
>
> Is there another solution for this problem?
> Or why was this patch not accepted to mainline?
>
> drivers/mmc/card/block.c | 6 ++++--
> drivers/mmc/host/omap_hsmmc.c | 6 ++++++
> include/linux/mmc/host.h | 3 +++
> 3 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index c742cfd..62250d8 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -2106,7 +2106,8 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
> struct mmc_blk_data *md;
> int devidx, ret;
>
> - devidx = find_first_zero_bit(dev_use, max_devices);
> + devidx = find_next_zero_bit(dev_use, max_devices,
> + card->host->devidx);
> if (devidx >= max_devices)
> return ERR_PTR(-ENOSPC);
> __set_bit(devidx, dev_use);
> @@ -2124,7 +2125,8 @@ 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);
> + md->name_idx = find_next_zero_bit(name_use, max_devices,
> + card->host->devidx);
> __set_bit(md->name_idx, name_use);
> } else
> md->name_idx = ((struct mmc_blk_data *)
> diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> index 7fb0753..0b45b48 100644
> --- a/drivers/mmc/host/omap_hsmmc.c
> +++ b/drivers/mmc/host/omap_hsmmc.c
> @@ -2059,6 +2059,12 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
> host->pbias_enabled = 0;
> host->vqmmc_enabled = 0;
>
> + if (pdev->dev.of_node) {
> + ret = of_alias_get_id(pdev->dev.of_node, "mmcblk");
> + if (ret >= 0)
> + host->mmc->devidx = ret;
> + }
> +
> ret = omap_hsmmc_gpio_init(mmc, host, pdata);
> if (ret)
> goto err_gpio;
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 83b81fd..4f071681 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -382,6 +382,9 @@ struct mmc_host {
> int dsr_req; /* DSR value is valid */
> u32 dsr; /* optional driver stage (DSR) value */
>
> + /* preferred mmc block device index (mmcblkX) */
> + unsigned int devidx;
> +
> unsigned long private[0] ____cacheline_aligned;
> };
>
>
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