On 19.07.2012 22:45, Jassi Brar wrote:
On 18 July 2012 19:41, Knut Wohlrab <knut.wohlrab@xxxxxxxxxxxx> wrote:
On 07/18/2012 03:47 PM, Jassi Brar wrote:
On 18 July 2012 15:19, Knut Wohlrab <knut.wohlrab@xxxxxxxxxxxx> wrote:
If a SD card is inserted at boot time, its "mmcblk0", the embedded
MMC (eMMC) device "mmcblk1". This makes it difficult to give the kernel
the
correct device for the eMMC root file system ("root=/dev/mmcblk?p1 ...").
How about root=UUID=<eMMC-partition> ?
Because we are talking about an embedded device, it is very difficult to get
a UUID of a eMMC partition into kernel command line with U-Boot. Handling of
UUID is also a big effort at board manufacturing.
I don't realize how bad is it if a common UUID is used on each cloned
eMMC(non-removable) of every instance of a device. But of course only
you know what's best for your product.
This problem can occur on many devices with embedded MMC and removable SD,
e.g. smart phones. So I think we should find an solution to define MMC scan
order or device number/name in a device tree.
I assume your issue is that due to async nature of mmc scanning, the
eMMC is detected later than external card, despite being the probe for
eMMC's slot initiated first ?
If so, we can do by simply associating 'N' of 'mmcblkN' with the slot
index i.e, mmc_host.index (instead of mmc_blk_data.name_idx). Which is
always in the order of probe calling. And we don't need to modify, or
expect more of, DT for that.
Do you mean something like
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -1536,7 +1536,7 @@ static struct mmc_blk_data
*mmc_blk_alloc_req(struct mmc_card *card,
*/
snprintf(md->disk->disk_name, sizeof(md->disk->disk_name),
- "mmcblk%d%s", md->name_idx, subname ? subname : "");
+ "mmcblk%d%s", card->host->index, subname ? subname : "");
blk_queue_logical_block_size(md->queue.queue, 512);
set_capacity(md->disk, size);
?
A first quick test looks promising. We will go on testing this.
Though I suspect there must be some
serious reason why it's not already done that way.
Anybody with an idea? Any serious reason?
Many thanks and best regards
Dirk
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