[U-Boot] [PATCH] syscon: update syscon_node_to_regmap to use the DM functions

[Tom Rini]

On Tue, Oct 30, 2018 at 02:44:29PM +0100, Patrick Delaunay wrote:
> + Update the function syscon_node_to_regmap() to force bound on
>   syscon uclass and directly use the list of device from DM.
> + Remove the static list syscon_list.
> 
> This patch avoid issue (crash) when syscon_node_to_regmap() is called
> before and after reallocation (list content is invalid).
> 
> Signed-off-by: Patrick Delaunay <patrick.delaunay at st.com>
> ---
> Hi
> 
> This patch is a modified (after Simon Glass review)
> and rebased version on v2018.11-rc3 for
> [U-Boot] syscon: reset node list syscon_list after relocation
> http://patchwork.ozlabs.org/patch/983139/
> 
> This patch correct a crash see on v2018.11-rc1 with my board stm32mp1
> for the command "reset", reproduced on v2018.11-rc3.
> 
> The crash is a side effect of 2 patches
> 1f6ca3f42f6edf143473159297f4c515b1cf36f6
>  sysreset: syscon: update regmap access to syscon
> 
> 23471aed5c33e104d6fa64575932577618543bec
>  board_f: Add reset status printing
> 
> With the first patch the syscon_node_to_regmap() is called
> each time that the class sysreset_syscon is probed.
> 
> => in v2018.09 probe is done only when reset is requested
> 
> NB: for stm32mp1, the node rcc_reboot in tagged pre-relocated to
>     support reset in pre-reloc phases (allow panic).
> 
> With the second patch, U-Boot probes all the sysreset uclass in preloc
> phase to allow to print the reset status, and the list is initialized
> in board_f / pre-reloc:
> 
> -> print_resetinfo
> --> uclass_first_device_err(UCLASS_SYSRESET, &dev);
> ---> syscon_reboot_probe()
> ----> syscon_node_to_regmap(node)
> -----> of_syscon_register()
> -------> list_add_tail(&syscon->list, &syscon_list);
> 
> During relocation, the content of syscon_list (static) is updated
> but the list use pointers allocated by malloc in pre-reloc phasis
> 
> And when I execute the reset command
> -> do_reset()
> --> reset_cpu()
> ---> sysreset_walk_halt(SYSRESET_COLD);
> ----> loop on device UCLASS_SYSRESET
> -----> syscon_reboot_probe()
> ------> syscon_node_to_regmap(node)
> -------> list_for_each_entry(entry, &syscon_list, list)
> 
> I have a crash here because the pointer syscon_list.next is invalid.
> 
> This patch solves the issue by using DM list for syscon uclass.
> 
> Tested on my board, the initial issue is solved and
> I check the behavior with dm_dump_all():
> the RCC driver is not binded/probed as syscon uclass by default
> (checked with dm tree) and correctly bounded and probed when
> it is necessary (before relocation: print_resetinfo() or after
> relocation for command reset).

So this is a regression we should fix, to be clear, yes?  Thanks!

-- 
Tom
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