Re: [maemo-leste] [PATCH] arm: Remove nokia_rx51 board

[Tom Rini <trini@konsulko.com>]

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On Thu, Jun 17, 2021 at 10:18:07AM +0300, Ivaylo Dimitrov wrote:
> 
> 
> On 17.06.21 г. 0:12 ч., Tom Rini wrote:
> > On Thu, Jun 17, 2021 at 12:03:15AM +0300, Ivaylo Dimitrov wrote:
> > > Hi Tom,
> > > 
> > > On 16.06.21 г. 20:37 ч., Tom Rini wrote:
> > > > On Wed, Jun 16, 2021 at 08:25:28PM +0300, Ivaylo Dimitrov wrote:
> > > > > Hi,
> > > > > 
> > > > > On 16.06.21 г. 15:13 ч., Tom Rini wrote:
> > > > > > On Wed, Jun 16, 2021 at 08:10:08AM -0400, Tom Rini wrote:
> > > > > > > On Wed, Jun 16, 2021 at 09:02:16AM +0300, Ivaylo Dimitrov wrote:
> > > > > > > > Hi,
> > > > > > > > 
> > > > > > > > On 15.06.21 г. 15:34 ч., Tom Rini wrote:
> > > > > > > > > On Tue, Jun 15, 2021 at 08:40:30AM +0300, Ivaylo Dimitrov wrote:
> > > > > > > > > > Hi,
> > > > > > > > > > 
> > > > > > > > > > On 22.05.21 г. 0:36 ч., Pali Rohár wrote:
> > > > > > > > > > > On Friday 21 May 2021 10:44:18 Tom Rini wrote:
> > > > > > > > > > > > On Wed, May 19, 2021 at 11:52:03AM -0400, Tom Rini wrote:
> > > > > > > > > > > > > On Wed, May 19, 2021 at 03:27:48PM +0200, Pali Rohár wrote:
> > > > > > > > > > > > > 
> > > > > > > > > > > > > > On Tuesday 18 May 2021 21:26:40 Tom Rini wrote:
> > > > > > > > > > > > > > > This board has not been converted to CONFIG_DM_USB by the deadline.
> > > > > > > > > > > > > > > Remove it.
> > > > > > > > > > > > > > 
> > > > > > > > > > > > > > I'm very disappointed that you want to remove Nokia N900 from U-Boot.
> > > > > > > > > > > > > > 
> > > > > > > > > > > > > > I was waiting waiting half of year because other developers did not
> > > > > > > > > > > > > > react to issues which were introduced and neither to patches which I
> > > > > > > > > > > > > > sent (+ trying to remind open issues). And also I was waiting another
> > > > > > > > > > > > > > half of year until other N900 related patches were merged. So the whole
> > > > > > > > > > > > > > slowdown was not caused by me, why it is taking so long.
> > > > > > > > > > > > > > 
> > > > > > > > > > > > > > Now there is still one N900 DM related patch waiting for review. I'm
> > > > > > > > > > > > > > converting code step by step.
> > > > > > > > > > > > > > 
> > > > > > > > > > > > > > So the ball is not on my side.
> > > > > > > > > > > > > 
> > > > > > > > > > > > > So, what patch(es) need to be applied to get DM_USB enabled?  Thanks.
> > > > > > > > > > > > 
> > > > > > > > > > > > I don't see any open patches from you that look related to enabling
> > > > > > > > > > > > DM_USB on the platform.  If you want to disable USB on the platform for
> > > > > > > > > > > > now instead, that's fine too.
> > > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > I tried to migrate the latest master to DM_USB, but unfortunately the
> > > > > > > > > > results are pretty much sad - adding OF_CONTROL (which is a prerequisite to
> > > > > > > > > > have DM_USB IIUC) and OF_BOARD (so binary to be compiled), adds ~100k to the
> > > > > > > > > > size of the u-boot binary, so it becomes 370284 bytes. Given that we have
> > > > > > > > > > less than 256k of storage space for the u-boot, the produced binary cannot
> > > > > > > > > > be used on n900 the same way current (no DM_USB) binary is used.
> > > > > > > > > > 
> > > > > > > > > > As I see it, there are not much options left - u-boot on N900 is not SPL, so
> > > > > > > > > > we can't use OF_PLATDATA, which in turn always links libfdt.
> > > > > > > > > > Also, if I read the code (usb-uclass.c) correctly, enabling DM_USB requires
> > > > > > > > > > the board to be converted to DT and this is way bigger change.
> > > > > > > > > > 
> > > > > > > > > > Please advice on how to proceed.
> > > > > > > > > 
> > > > > > > > > Please post your WIP patches, thanks.
> > > > > > > > > 
> > > > > > > > 
> > > > > > > > Sorry, I am not sure I understand what patches you want me to post:
> > > > > > > > 
> > > > > > > > WDT patch has already been sent couple of months ago -
> > > > > > > > https://lists.denx.de/pipermail/u-boot/2021-March/443868.html
> > > > > > > > Do you want it to be rebased and resend?
> > > > > > > > 
> > > > > > > > DM_USB, I just started writing one and I immediately hit the OF_CONTROL
> > > > > > > > requirement. Enabling OF_CONTROL requires a full blown migration to DT,
> > > > > > > > which is a huge task and not really equal to "Please update the board to use
> > > > > > > > CONFIG_DM_USB...". Without OF_CONTROL, I simply get link failures:
> > > > > > > > 
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > DWARF error: could not find abbrev number 3998
> > > > > > > > /tmp/cc0BOqms.ltrans0.ltrans.o: in function `usb_child_post_bind':
> > > > > > > > <artificial>:(.text+0x5672): undefined reference to
> > > > > > > > `ofnode_read_u32_default'
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > <artificial>:(.text+0x568c): undefined reference to
> > > > > > > > `ofnode_read_u32_default'
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > /tmp/cc0BOqms.ltrans0.ltrans.o: in function `usb_scan_device':
> > > > > > > > <artificial>:(.text+0x6c84): undefined reference to `ofnode_first_subnode'
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > <artificial>:(.text+0x6c96): undefined reference to `ofnode_read_u32'
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > <artificial>:(.text+0x6ca4): undefined reference to `ofnode_next_subnode'
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > /tmp/cc0BOqms.ltrans0.ltrans.o:(.u_boot_list_2_uclass_driver_2_usb+0x8):
> > > > > > > > undefined reference to `dm_scan_fdt_dev'
> > > > > > > > /usr/lib/gcc-cross/arm-linux-gnueabi/8/../../../../arm-linux-gnueabi/bin/ld:
> > > > > > > > /tmp/cc0BOqms.ltrans0.ltrans.o:(.u_boot_list_2_uclass_driver_2_usb_hub+0x8):
> > > > > > > > undefined reference to `dm_scan_fdt_dev'
> > > > > > > > 
> > > > > > > > Fixing those requires enabling of OF_CONTROL and this in turn means the
> > > > > > > > board must be migrated to DT, unless I am missing something. That's why my
> > > > > > > > "please advice..." stance.
> > > > > > > 
> > > > > > > Please post the patches that bring you to the above link errors, yes,
> > > > > > > thanks.
> > > > > > 
> > > > > > To be clearer, finish up a patch that completes the migration but is too
> > > > > > large to install on the hardware so that others can take a look.
> > > > > 
> > > > > I am not sure I understand that - a patch that completes the migration to
> > > > > DM_USB cannot be done ATM as the binary does not link without OF_CONTROL.
> > > > > And I am not going to enable OF_CONTROL as this means I will have to migrate
> > > > > everything to DT. That's why I enable DM_USB only - see reply to the other
> > > > > mail.
> > > > 
> > > > My advise is to provide a linkable but not runnable (or, only runnable
> > > > in QEMU, the problem is the fixed layout of the actual device flash,
> > > > right?) patch so that we can figure out how and what needs to be tuned
> > > > where so that we can see what to do about this platform.
> > > > 
> > > 
> > > What about the following patch (once you confirm I am on the right track, I
> > > will send a proper patch as well). Enabling thumb is a must, otherwise
> > > binary does not fit. With the below changes code compiles and runs on a real
> > > HW:
> > 
> > Wait, why is thumb disabled?  That's something I'd really like to know
> > why on as my first guess is there's units with old enough cores that
> > have some thumb errata maybe?
> 
> omap3 in N900 suffers from ARM errata 430973, I guess that's why -mthumb was
> disabled back then. I implemented N900 specific workaround to set the IBE
> bit in ACR in the board code, but I don't see flush BTAC/BTB being executed
> on context switch (if there are context switches at all). The only places I
> was able to find that flush BTAC/BTB instruction are on startup
> (cpu_init_cp15()) and cache invalidate (invalidate_icache_all()).
> 
> BTW the code in cpu_init_cp15() is buggy, as flush is executed before IBE
> bit in ACR is set, making that flush effectively a noop on boards where IBE
> bit was not set by the previous stage loader, but that's another story not
> affecting N900 :).

A separate thread / patch on that would be much appreciated :)

> So, as soon as there are no context switches in u-boot that may land
> different code on a same physical address, we should be safe. Could you
> confirm this is the case? Is there virtual addressing? Multiple processes?

The only place I'm not 100% sure we wouldn't have virtual addressing
would be when you start to involve the EFI loader and in turn EFI
applications are running.  But we're specifically disabling this here
(and I don't think it's useful on this era hardware anyhow).

> > For the second part, how are you binding
> > the device?  And oh, we didn't disable the EFI loader support already?
> 
> Yeah, looks like selecting libfdt automagically selects a whole bunch of
> other things (like CMD_FDT and OF_LIBFDT_OVERLAY)
> 
> > Yeah, that would be another pretty easy choice to win back a bunch of
> > space.  So yes, this is certainly on the right track, thanks!
> > 
> 
> Ok, we'll send a proper patch series as soon as it is confirmed that it is
> safe to enable -mthumb.

Thanks.

> In the meanwhile, could you please have a look at the WDT patch Pali posted
> back then?

It's been merged to -next for a little while now, via the TI tree.

-- 
Tom

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