On Thu, Jul 23, 2020 at 11:14:02AM +0200, Arnd Bergmann wrote:

On Thu, Jul 23, 2020 at 11:02 AM Krzysztof Kozlowski [off-list ref] wrote:

quoted

On Thu, Jul 23, 2020 at 10:48:19AM +0200, Arnd Bergmann wrote:

quoted

On Thu, Jul 23, 2020 at 9:39 AM Krzysztof Kozlowski [off-list ref] wrote:

quoted

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.

quoted

quoted

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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