[PATCH u-boot-marvell 00/13] Yet another kwboot improvements

[Pali Rohár]

On Wednesday 27 October 2021 15:52:47 Pali Rohár wrote:
> On Wednesday 27 October 2021 07:09:42 Stefan Roese wrote:
> > On 26.10.21 20:48, Pali Rohár wrote:
> > > On Tuesday 26 October 2021 16:21:02 Stefan Roese wrote:
> > > > On 26.10.21 14:40, Pali Rohár wrote:
> > > > > My another guess there could be a problem is usage of stack. Maybe it is
> > > > > possible that register with stack pointer is not initialized after the
> > > > > full transfer when going to execute main image. Same arm baudrate change
> > > > > code is used after the SPL and before main U-Boot, and the first
> > > > > instruction is "push". Maybe modifying the arm code to not use stack
> > > > > when switching the baudrate back to 115200 could also help. I will look
> > > > > at it.
> > > > 
> > > > Thanks.
> > > 
> > > Here is dirty hack patch which completely disable calling code for
> > > changing baudrate back to 115200 on ARM side:
> > > 
> > > diff --git a/tools/kwboot.c b/tools/kwboot.c
> > > index 5f4ff673972e..00d58a239c71 100644
> > > --- a/tools/kwboot.c
> > > +++ b/tools/kwboot.c
> > > @@ -1070,17 +1070,17 @@ kwboot_xmodem(int tty, const void *_img, size_t size, int baudrate)
> > >   		return rc;
> > >   	if (baudrate) {
> > > -		char buf[sizeof(kwb_baud_magic)];
> > > -
> > > -		kwboot_printv("Waiting 1s for baudrate change magic\n");
> > > -		rc = kwboot_tty_recv(tty, buf, sizeof(buf), 1000);
> > > -		if (rc)
> > > -			return rc;
> > > -
> > > -		if (memcmp(buf, kwb_baud_magic, sizeof(buf))) {
> > > -			errno = EPROTO;
> > > -			return -1;
> > > -		}
> > > +//		char buf[sizeof(kwb_baud_magic)];
> > > +//
> > > +//		kwboot_printv("Waiting 1s for baudrate change magic\n");
> > > +//		rc = kwboot_tty_recv(tty, buf, sizeof(buf), 1000);
> > > +//		if (rc)
> > > +//			return rc;
> > > +//
> > > +//		if (memcmp(buf, kwb_baud_magic, sizeof(buf))) {
> > > +//			errno = EPROTO;
> > > +//			return -1;
> > > +//		}
> > >   		kwboot_printv("\nChanging baudrate back to 115200 Bd\n\n");
> > >   		rc = kwboot_tty_change_baudrate(tty, 115200);
> > > @@ -1551,8 +1551,8 @@ kwboot_img_patch(void *img, size_t *size, int baudrate)
> > >   		 * This code is appended after the data part of the image and
> > >   		 * execaddr is changed to execute this code before U-Boot proper.
> > >   		 */
> > > -		kwboot_printv("Injecting code for changing baudrate back\n");
> > > -		_copy_baudrate_change_code(hdr, size, 1, baudrate, 115200);
> > > +//		kwboot_printv("Injecting code for changing baudrate back\n");
> > > +//		_copy_baudrate_change_code(hdr, size, 1, baudrate, 115200);
> > 
> > I do have this here in my version as well:
> > 
> > 		/* Update the 32-bit data checksum */
> > 		*kwboot_img_csum32_ptr(img) = kwboot_img_csum32(img);
> > 
> > 		/* recompute header size */
> > 		hdrsz = kwbheader_size(hdr);
> > 
> > So I'm using the newer version, just to be sure.
> 
> Ok, I probably generated diff against older version, but you have
> figured out how to apply it.
> 
> > >   		/* recompute header size */
> > >   		hdrsz = kwbheader_size(hdr);
> > > 
> > > As main U-Boot binary on ARM resets UART, it means that baudrate is
> > > properly set to 115200. Probably beginning of the U-Boot output could be
> > > lost but at least console should start.
> > > 
> > > Could you try this patch if it starts working now?
> > 
> > Okay, applied this patch and and booting with different baudrates works
> > on this board again (tested with 230400):
> > 
> >  96 %
> > [......................................................................]
> >  98 %
> > [......................................................................]
> >  99 % [................       ]
> > Done
> > Finishing transfer
> > 
> > Changing baudrate back to 115200 Bd
> > 
> > [Type Ctrl-\ + c to quit]
> > 
> > 
> > U-Boot 2021.10-00908-gc129aa2f173a-dirty (Oct 27 2021 - 07:05:39 +0200)
> > 
> > SoC:   MV78260-B0 at 1333 MHz
> > I2C:   ready
> > DRAM:  2 GiB (667 MHz, 64-bit, ECC not enabled)
> > Loading Environment from SPIFlash... SF: Detected m25p128 with page size 256
> > Bytes, erase size 256 KiB, total 16 MiB
> > OK
> > Model: Marvell Armada XP theadorable
> > ...
> > 
> > 
> > Thanks,
> > Stefan
> 
> Perfect! So it really looks like that issue is in the code which resets
> baudrate back to the value 115200.
> 
> I have there another diff which removes usage of the stack in code which
> resets baudrate back to default value:
> 
> diff --git a/tools/kwboot.c b/tools/kwboot.c
> index b56c9a0c8104..8f0e50501398 100644
> --- a/tools/kwboot.c
> +++ b/tools/kwboot.c
> @@ -1444,6 +1444,11 @@ _inject_baudrate_change_code(void *img, size_t *size, int pre,
>  	memcpy(code, kwboot_baud_code, codesz - 8);
>  	*(uint32_t *)(code + codesz - 8) = cpu_to_le32(old_baud);
>  	*(uint32_t *)(code + codesz - 4) = cpu_to_le32(new_baud);
> +
> +	if (!pre) {

Ou, there is a mistake, it should be "if (pre) {"

> +		*(uint32_t *)code = cpu_to_le32(0xe1a00000); /* arm nop */
> +		*(uint32_t *)(code + codesz - 4*7) = cpu_to_le32(0xe12fff1e); /* bx lr */
> +	}
>  }
>  
>  static int
> 
> Could you try to apply this change instead of my previous one?