Hi Simon,
On Thu, Apr 11, 2019 at 10:39 AM Simon Horman <horms@xxxxxxxxxxxx> wrote:
> On Wed, Apr 03, 2019 at 08:21:48PM +0200, Geert Uytterhoeven wrote:
> > During PSCI system suspend, R-Car Gen3 SoCs are powered down, and all
> > IPMMU state is lost. Hence after s2ram, devices wired behind an IPMMU,
> > and configured to use it, will see their DMA operations hang.
> >
> > To fix this, restore all IPMMU contexts, and re-enable all active
> > micro-TLBs during system resume.
> >
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > ---
> > This patch takes a different approach than the BSP, which implements a
> > bulk save/restore of all registers during system suspend/resume.
> >
> > v2:
> > - Drop PSCI checks.
> > ---
> > drivers/iommu/ipmmu-vmsa.c | 47 +++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 46 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
> > index 56e84bcc9532e1ce..408ad0b2591925e0 100644
> > --- a/drivers/iommu/ipmmu-vmsa.c
> > +++ b/drivers/iommu/ipmmu-vmsa.c
> > @@ -36,7 +36,10 @@
> > #define arm_iommu_detach_device(...) do {} while (0)
> > #endif
> >
> > -#define IPMMU_CTX_MAX 8U
> > +#define IPMMU_CTX_MAX 8U
> > +#define IPMMU_CTX_INVALID -1
> > +
> > +#define IPMMU_UTLB_MAX 48U
> >
> > struct ipmmu_features {
> > bool use_ns_alias_offset;
> > @@ -58,6 +61,7 @@ struct ipmmu_vmsa_device {
> > spinlock_t lock; /* Protects ctx and domains[] */
> > DECLARE_BITMAP(ctx, IPMMU_CTX_MAX);
> > struct ipmmu_vmsa_domain *domains[IPMMU_CTX_MAX];
>
> It might be possible to save a bit of memory on Gen 2 systems by
> making IPMMU_UTLB_MAX 32 when the driver is compiled for such systems.
This comment applies to the line below, right?
> > + s8 utlb_ctx[IPMMU_UTLB_MAX];
So it's just 16 bytes, not 16 pointers.
Doing so would reduce struct ipmmu_vmsa_device from 148 to 132 bytes.
Given that structure is allocated by devm_kzalloc(), and devres alignment
was increased in commit a66d972465d15b1d ("devres: Align data[] to
ARCH_KMALLOC_MINALIGN"), I guess it won't make a difference.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
