Re: [PATCH 2/3] usb: gadget: dfu: Progressive erase if file is a mtd

[Sascha Hauer <s.hauer@pengutronix.de>]

Hi Jules,

On Tue, Mar 24, 2020 at 04:46:46PM +0100, Jules Maselbas wrote:
> When downloading a firmware into a big flash partition the erase
> operation can take a long time to be complete from few seconds to
> minutes in extreme cases. During the erase the DFU gadget does not
> respond to any USB setup request, the host only see a stalled USB
> endpoint and cannot get responses from DFU_GETSTATE nor DFU_GETSTATUS.
> 
> After 5 seconds without any updates the host will abort the DFU
> transfer and return an error (when using dfu-util).
> 
> For instance I have a 2MB partition that takes 25 seconds to erase,
> this erase cannot be done in one step as it takes too much time or it
> should be done in the manifestation phase, see previous patch.
> 
> This patch modify the erase behavior when downloading a new firmware.
> If the updated file is a mtd partition then the DFU gadget will do
> a progressive erase by erasing the least amount of required blocks
> before writing a new chunk into the mtd device.
> 
> Signed-off-by: Jules Maselbas <jmaselbas@kalray.eu>
> ---
>  drivers/usb/gadget/dfu.c | 21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/dfu.c b/drivers/usb/gadget/dfu.c
> index fef6f3e3a..592586db1 100644
> --- a/drivers/usb/gadget/dfu.c
> +++ b/drivers/usb/gadget/dfu.c
> @@ -55,6 +55,8 @@
>  #include <libbb.h>
>  #include <init.h>
>  #include <fs.h>
> +#include <ioctl.h>
> +#include <linux/mtd/mtd-abi.h>
>  
>  #define USB_DT_DFU			0x21
>  
> @@ -132,6 +134,10 @@ struct file_list_entry *dfu_file_entry;
>  static int dfufd = -EINVAL;
>  static struct file_list *dfu_files;
>  static int dfudetach;
> +static struct mtd_info_user dfu_mtdinfo;
> +static loff_t dfu_written;
> +static loff_t dfu_erased;
> +static int prog_erase;

These are not initialized, this works for the first file updated via
DFU, but what about the following ones?

>  
>  /* USB DFU functional descriptor */
>  static struct usb_dfu_func_descriptor usb_dfu_func = {
> @@ -327,8 +333,16 @@ static void dfu_cleanup(struct f_dfu *dfu)
>  static void dn_complete(struct usb_ep *ep, struct usb_request *req)
>  {
>  	struct f_dfu		*dfu = req->context;
> +	loff_t size;
>  	int ret;
>  
> +	if (prog_erase && (dfu_written + req->length) > dfu_erased) {
> +		size = roundup(req->length, dfu_mtdinfo.erasesize);
> +		erase(dfufd, size, dfu_erased);

You should check the return value here.

> +		dfu_erased += size;
> +	}
> +
> +	dfu_written += req->length;
>  	ret = write(dfufd, req->buf, req->length);
>  	if (ret < (int)req->length) {
>  		perror("write");
> @@ -493,7 +507,12 @@ static int dfu_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
>  			}
>  
>  			if (!(dfu_file_entry->flags & FILE_LIST_FLAG_SAFE)) {
> -				ret = erase(dfufd, ERASE_SIZE_ALL, 0);
> +				ret = ioctl(dfufd, MEMGETINFO, &dfu_mtdinfo);
> +				if (ret) /* not a mtd */
> +					ret = erase(dfufd, ERASE_SIZE_ALL, 0);
> +				else
> +					prog_erase = 1;

I am not aware of any non mtd devices that need erase. I think you can
drop the full erase here.

Sascha

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