Messages in this thread | | | Date | Thu, 23 Jul 2020 12:01:36 +0200 | From | Krzysztof Kozlowski <> | Subject | Re: [PATCH 14/23] memory: ti-emif-pm: Fix cast to iomem pointer |
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On Thu, Jul 23, 2020 at 11:14:02AM +0200, Arnd Bergmann wrote: > On Thu, Jul 23, 2020 at 11:02 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: > > On Thu, Jul 23, 2020 at 10:48:19AM +0200, Arnd Bergmann wrote: > > > On Thu, Jul 23, 2020 at 9:39 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: > > > > > > > > Cast pointer to iomem memory properly to fix sparse warning: > > > > > > > > drivers/memory/ti-emif-pm.c:251:38: warning: incorrect type in argument 1 (different address spaces) > > > > drivers/memory/ti-emif-pm.c:251:38: expected void const volatile [noderef] __iomem *addr > > > > drivers/memory/ti-emif-pm.c:251:38: got void * > > > > > > > > Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> > > > > --- > > > > drivers/memory/ti-emif-pm.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/memory/ti-emif-pm.c b/drivers/memory/ti-emif-pm.c > > > > index 9c90f815ad3a..6c747c1e98cb 100644 > > > > --- a/drivers/memory/ti-emif-pm.c > > > > +++ b/drivers/memory/ti-emif-pm.c > > > > @@ -248,7 +248,7 @@ MODULE_DEVICE_TABLE(of, ti_emif_of_match); > > > > static int ti_emif_resume(struct device *dev) > > > > { > > > > unsigned long tmp = > > > > - __raw_readl((void *)emif_instance->ti_emif_sram_virt); > > > > + __raw_readl((void __iomem *)emif_instance->ti_emif_sram_virt); > > > > > > > > > > Maybe this shouldn't even be __raw_readl(), but instead READ_ONCE()? > > > > Won't readl() be enough? Indeed it looks problematic. > > readl() won't work on big-endian kernels, since this is a byte comparison.
Ah, right.
> > > > The other accesses in this file don't use MMIO wrappers either but just treat > > > it as a pointer. The effect would be the same though. > > > > I think all the reads and writes are with readl() and writel(). > > I actually see only one other access: > > copy_addr = sram_exec_copy(emif_data->sram_pool_code, > (void *)emif_data->ti_emif_sram_virt, > &ti_emif_sram, ti_emif_sram_sz); > > and this one ends up in a memcpy() that does not perform any byte > swapping or barriers.
At least the barrier would come through mutex in sram_exec_copy() and later spin locks for page table manipulation.
Anyway, I do not have the HW to test the changes or to confirm whether this is real issue. I guess the driver author/owner should follow up on this report.
Best regards, Krzysztof
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