Messages in this thread | | | From | Loic Poulain <> | Date | Thu, 30 Mar 2023 15:22:47 +0200 | Subject | Re: [PATCH] mfd: syscon: Use of_io_request_and_map() for IO mapping |
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Hi Arnd,
On Thu, 30 Mar 2023 at 14:45, Arnd Bergmann <arnd@arndb.de> wrote: > > On Thu, Mar 30, 2023, at 13:42, Lee Jones wrote: > > On Mon, 20 Mar 2023, Loic Poulain wrote: > > > >> Use of_io_request_and_map() instead of of_iomap() so that the > >> region is reserved and protected, i.e reported in /proc/iomem > >> and not accessible from user side (CONFIG_IO_STRICT_DEVMEM). > >> > >> Signed-off-by: Loic Poulain <loic.poulain@linaro.org> > >> --- > >> drivers/mfd/syscon.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c > >> index bdb2ce7ff03b..7e6d4edda118 100644 > >> --- a/drivers/mfd/syscon.c > >> +++ b/drivers/mfd/syscon.c > >> @@ -60,7 +60,7 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk) > >> goto err_map; > >> } > >> > >> - base = of_iomap(np, 0); > >> + base = of_io_request_and_map(np, 0, NULL); > >> if (!base) { > >> ret = -ENOMEM; > >> goto err_map; > > > > Looks sane though. > > > > Arnd, do you have an opinion? > > Thanks for pinging me. I would indeed expect this to cause > problems, as syscon mappings are likely to be used in a way > that is not entirely clean, with other devices defining > overlapping ranges.
Isn't syscon exactly here to address that collision/overlapping issue? From a syscon perspective, it seems to be handled correctly at least since the mapping is only setup once, with the first user device (in syscon_node_to_regmap). Or are you thinking about non syscon devices overlapping the syscon area?
> > For any other driver, the change makes a lot of sense after > checking the DT file, but for syscon in particular I don't > think it's even realistic to check all users. > > Arnd
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