Re: [PATCH] mmc: omap_hsmmc: fix initialization order of mmc block devices
From: Heiko Schocher
Date: Tue Oct 13 2015 - 03:44:37 EST
Hello Lokesh,
Am 13.10.2015 um 08:46 schrieb Lokesh Vutla:
+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.
Good tip ... I do not know, if it is possible to update U-Boot
on this boards...
Current U-Boot says:
U-Boot 2013.01.01_heads/master-gc7900a0 (2015-05-06 - 20:37:15)
I2C: ready
DRAM: 512 MiB
[...]
U-Boot# mmc rescan
U-Boot# mmc part
Partition Map for MMC device 0 -- Partition Type: DOS
Part Start Sector Num Sectors UUID Type
1 63 144522 000ce343-01 0e Boot
2 144585 659861 000ce343-02 83
U-Boot# part uuid mmc 0:2 uuid
Unknown command 'part' - try 'help'
U-Boot#
So, if this patch has no chance for mainline, please let me
know it, thanks!
bye,
Heiko
[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;
};
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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