| Message ID | 20201001161740.29064-4-nsaenzjulienne@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Default to 32-bit wide ZONE_DMA | expand |
On Thu, Oct 01, 2020 at 06:17:39PM +0200, Nicolas Saenz Julienne wrote: > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index e1a69a618832..3c3f462466eb 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -43,8 +43,6 @@ > #include <asm/tlb.h> > #include <asm/alternative.h> > > -#define ARM64_ZONE_DMA_BITS 30 > - > /* > * We need to be able to catch inadvertent references to memstart_addr > * that occur (potentially in generic code) before arm64_memblock_init() > @@ -388,8 +386,14 @@ void __init arm64_memblock_init(void) > early_init_fdt_scan_reserved_mem(); > > if (IS_ENABLED(CONFIG_ZONE_DMA)) { > - zone_dma_bits = ARM64_ZONE_DMA_BITS; > - arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS); > + /* > + * early_init_dt_scan() might alter zone_dma_bits based on the > + * device's DT. Otherwise, have it cover the 32-bit address > + * space. > + */ > + if (zone_dma_bits == ZONE_DMA_BITS_DEFAULT) > + zone_dma_bits = 32; > + arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); So here we assume that if zone_dma_bits is 24, it wasn't initialised. I think it may be simpler if we just set it in setup_machine_fdt() to 32 or 30 if RPi4. This way we don't have to depend on what the core kernel sets.
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index e1a69a618832..3c3f462466eb 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -43,8 +43,6 @@ #include <asm/tlb.h> #include <asm/alternative.h> -#define ARM64_ZONE_DMA_BITS 30 - /* * We need to be able to catch inadvertent references to memstart_addr * that occur (potentially in generic code) before arm64_memblock_init() @@ -388,8 +386,14 @@ void __init arm64_memblock_init(void) early_init_fdt_scan_reserved_mem(); if (IS_ENABLED(CONFIG_ZONE_DMA)) { - zone_dma_bits = ARM64_ZONE_DMA_BITS; - arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS); + /* + * early_init_dt_scan() might alter zone_dma_bits based on the + * device's DT. Otherwise, have it cover the 32-bit address + * space. + */ + if (zone_dma_bits == ZONE_DMA_BITS_DEFAULT) + zone_dma_bits = 32; + arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); } if (IS_ENABLED(CONFIG_ZONE_DMA32))
The Raspberry Pi 4 needs two DMA zones as some of its devices can only DMA into the 30-bit physical address space. We solved that by creating an extra ZONE_DMA covering the 30-bit. It turns out that creating extra zones unnecessarily broke Kdump on large systems. So default to a single 32-bit wide ZONE_DMA and only define both zones if running on RPi4. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> --- arch/arm64/mm/init.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)