[U-Boot] [PATCH 1/1] blk: set log2blksz in blk_create_device()

[Heinrich Schuchardt]

On 10/30/19 2:49 AM, Simon Glass wrote:
> Hi Heinrich,
>
> On Fri, 25 Oct 2019 at 04:15, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>>
>> The ext4 file system requires log2blksz to be set. So when setting the
>> block size on the block descriptor we should fill this field too.
>>
>> This fixes a problem with EFI block devices providing ext4 partitions, cf.
>> https://lists.denx.de/pipermail/u-boot/2019-October/387702.html.
>>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> ---
>>   drivers/block/blk-uclass.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>
> Reviewed-by: Simon Glass <sjg at chromium.org>
>
> But I wonder if blk_create_device() should change to take log2blksz as
> its parameter and calculate blksz?

CD-ROM mode 2 has 2336 data bytes,
CD-ROM XA Mode 2, Form 2 has 2324 data bytes
according to https://en.wikipedia.org/wiki/CD-ROM.

So we cannot assume that blksz is a power of two in the general case.

LOG2() is behaving a bit erratically for numbers that are not a power of
two (in contrast to what ilog2() does):

LOG2(2048) = 11
LOG2(2049) = 11
LOG2(2324) = 15
LOG2(2336) = 15
LOG2(3072) = 11
LOG2(4096) = 12

ilog2(2048) = 11
ilog2(2049) = 11
ilog2(2324) = 11
ilog2(2336) = 11
ilog2(3072) = 11
ilog2(4096) = 12

But if we ever add an ISO 9660 file system driver, we will not be able
to use log2blksz anyway. So I think we can stick with LOG2().

Best regards

Heinrich

>
>
>> diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
>> index e8f58b3f5e..ca8978f0e1 100644
>> --- a/drivers/block/blk-uclass.c
>> +++ b/drivers/block/blk-uclass.c
>> @@ -580,6 +580,7 @@ int blk_create_device(struct udevice *parent, const char *drv_name,
>>          desc = dev_get_uclass_platdata(dev);
>>          desc->if_type = if_type;
>>          desc->blksz = blksz;
>> +       desc->log2blksz = LOG2(desc->blksz);
>>          desc->lba = lba;
>>          desc->part_type = PART_TYPE_UNKNOWN;
>>          desc->bdev = dev;
>> --
>> 2.23.0
>>
>
> Regards,
> Simon
>