Messages in this thread | | | Date | Wed, 1 May 2013 11:09:55 -0700 | From | "Christian Daudt" <> | Subject | Re: [PATCH] ARM: bcm281xx: Add L2 support for Rev A2 chips |
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Hi Will, Thanks for your feedback. See below for answers.
On 13-05-01 03:37 AM, Will Deacon wrote: > Hi Christian, > > Thanks for CC'ing me. > > On Tue, Apr 30, 2013 at 07:38:09PM +0100, Christian Daudt wrote: >> Rev A2 SoCs have an unorthodox memory re-mapping and this needs >> to be reflected in the cache operations. >> This patch adds new outer cache functions for the l2x0 driver >> to support this SoC revision. It also adds a new compatible >> value for the cache to enable this functionality. > This is a pretty weird thing you've managed to build here... No argument here. >> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c >> index c465fac..6edba13 100644 >> --- a/arch/arm/mm/cache-l2x0.c >> +++ b/arch/arm/mm/cache-l2x0.c >> @@ -523,6 +523,162 @@ static void aurora_flush_range(unsigned long start, unsigned long end) >> } >> } >> >> +/* >> + * For certain Broadcom SoCs, depending on the address range, different offsets >> + * need to be added to the address before passing it to L2 for >> + * invalidation/clean/flush >> + * >> + * Section Address Range Offset EMI >> + * 1 0x00000000 - 0x3FFFFFFF 0x80000000 VC >> + * 2 0x40000000 - 0xBFFFFFFF 0x40000000 SYS >> + * 3 0xC0000000 - 0xFFFFFFFF 0x80000000 VC > Hmm, so am I right in thinking that the `Broadcom addresses' for section 1 > and 2 overlap? It would also be worth describing which physical addresses > Linux actually wants to use; where is the memory in the physical memory map > for devices with this L2 controller? I've clarified this internally. Yes, there is an overlap, and because of that section 1 can't actually be used. I'm going to clear up the patch to remove the section one calculations to simplify it. >> + * When the start and end addresses have crossed two different sections, we >> + * need to break the L2 operation into two, each within its own section. >> + * For example, if we need to invalidate addresses starts at 0xBFFF0000 and >> + * ends at 0xC0001000, we need do invalidate 1) 0xBFFF0000 - 0xBFFFFFFF and 2) >> + * 0xC0000000 - 0xC0001000 >> + * >> + * Note 1: >> + * By breaking a single L2 operation into two, we may potentially suffer some >> + * performance hit, but keep in mind the cross section case is very rare >> + * >> + * Note 2: >> + * We do not need to handle the case when the start address is in >> + * Section 1 and the end address is in Section 3, since it is not a valid use >> + * case >> + */ >> + >> +#define BCM_VC_EMI_SEC1_START_ADDR 0x00000000UL >> +#define BCM_VC_EMI_SEC1_END_ADDR 0x3FFFFFFFUL >> +#define BCM_SYS_EMI_START_ADDR 0x40000000UL >> +#define BCM_SYS_EMI_END_ADDR 0xBFFFFFFFUL >> +#define BCM_VC_EMI_SEC3_START_ADDR 0xC0000000UL >> +#define BCM_VC_EMI_SEC3_END_ADDR 0xFFFFFFFFUL > Seems a bit odd defining the END_ADDRs here, I'd just use strict '<' against > the start of the next section in your code. Makes sense. Removed. >> +#define BCM_SYS_EMI_OFFSET 0x40000000UL >> +#define BCM_VC_EMI_OFFSET 0x80000000UL >> + >> +static inline int bcm_addr_is_sys_emi(unsigned long addr) >> +{ >> + return (addr >= BCM_SYS_EMI_START_ADDR) && >> + (addr <= BCM_SYS_EMI_END_ADDR); >> +} >> + >> +static inline unsigned long bcm_l2_phys_addr(unsigned long addr) >> +{ >> + if (bcm_addr_is_sys_emi(addr)) >> + return addr + BCM_SYS_EMI_OFFSET; >> + else >> + return addr + BCM_VC_EMI_OFFSET; >> +} >> + >> +static void bcm_inv_range(unsigned long start, unsigned long end) >> +{ >> + unsigned long new_start, new_end; >> + >> + if (unlikely(end <= start)) >> + return; >> + >> + new_start = bcm_l2_phys_addr(start); >> + new_end = bcm_l2_phys_addr(end); >> + >> + /* normal case, no cross section between start and end */ >> + if (likely((bcm_addr_is_sys_emi(start) && bcm_addr_is_sys_emi(end)) || >> + (!bcm_addr_is_sys_emi(start) && !bcm_addr_is_sys_emi(end)))) { > You could avoid evaluating bcm_addr_is_sys_emi twice for each address. In > fact, you know start < end, so you just need to check start >= EMI_START and > end < EMI_END. This test is to confirm that the range is completely within 1 section, so a single test won't do that - with the test as-is, the code after this 'if' already knows that there is section overlap. But I'll be removing section 1 handling and that will simplify things.
thanks, csd
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