[U-Boot] [PATCH V2 2/2] dfu: fix some issues with reads/uploads

[Lukasz Majewski <l.majewski@samsung.com>]

Hi Stephen,

> From: Stephen Warren <swarren@nvidia.com>
> 
> DFU read support appears to rely upon dfu->read_medium() updating the
> passed-by-reference len parameter to indicate the remaining size
> available for reading.
> 
> dfu_read_medium_mmc() never does this, and the implementation of
> dfu_read_medium_nand() will only work if called just once; it
> hard-codes the value to the total size of the NAND device
> irrespective of read offset.
> 
> I believe that overloading dfu->read_medium() is confusing. As such,
> this patch introduces a new function dfu->get_medium_size() which can
> be used to explicitly find out the medium size, and nothing else.
> dfu_read() is modified to use this function to set the initial value
> for dfu->r_left, rather than attempting to use the side-effects of
> dfu->read_medium() for this purpose.
> 
> Due to this change, dfu_read() must initially set dfu->b_left to 0,
> since no data has been read.
> 
> dfu_read_buffer_fill() must also be modified not to adjust dfu->r_left
> when simply copying data from dfu->i_buf_start to the upload request
> buffer. r_left represents the amount of data left to be read from HW.
> That value is not affected by the memcpy(), but only by calls to
> dfu->read_medium().
> 
> After this change, I can read from either a 4MB or 1.5MB chunk of a
> 4MB eMMC boot partion with CONFIG_SYS_DFU_DATA_BUF_SIZE==1MB. Without
> this change, attempting to do that would result in DFU read returning
> no data at all due to r_left never being set.
> 
> Signed-off-by: Stephen Warren <swarren@nvidia.com>

Applied to u-boot-dfu

Thanks for the patch.

-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group