lkml.org 
[lkml]   [2019]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/2] powerpc/83xx: map IMMR with a BAT.
From
Date


Le 14/09/2019 à 16:34, Scott Wood a écrit :
> On Fri, 2019-08-23 at 12:50 +0000, Christophe Leroy wrote:
>> On mpc83xx with a QE, IMMR is 2Mbytes.
>> On mpc83xx without a QE, IMMR is 1Mbytes.
>> Each driver will map a part of it to access the registers it needs.
>> Some driver will map the same part of IMMR as other drivers.
>>
>> In order to reduce TLB misses, map the full IMMR with a BAT.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>> arch/powerpc/platforms/83xx/misc.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/arch/powerpc/platforms/83xx/misc.c
>> b/arch/powerpc/platforms/83xx/misc.c
>> index f46d7bf3b140..1e395b01c535 100644
>> --- a/arch/powerpc/platforms/83xx/misc.c
>> +++ b/arch/powerpc/platforms/83xx/misc.c
>> @@ -18,6 +18,8 @@
>> #include <sysdev/fsl_soc.h>
>> #include <sysdev/fsl_pci.h>
>>
>> +#include <mm/mmu_decl.h>
>> +
>> #include "mpc83xx.h"
>>
>> static __be32 __iomem *restart_reg_base;
>> @@ -145,6 +147,14 @@ void __init mpc83xx_setup_arch(void)
>> if (ppc_md.progress)
>> ppc_md.progress("mpc83xx_setup_arch()", 0);
>>
>> + if (!__map_without_bats) {
>> + int immrsize = IS_ENABLED(CONFIG_QUICC_ENGINE) ? SZ_2M :
>> SZ_1M;
>
> Any reason not to unconditionally make it 2M? After all, the kernel being
> built with CONFIG_QUICC_ENGINE doesn't mean that the hardware you're running
> on has it...
>

Euh .. ok. I didn't see it that way, but you are right.

Do you think it is not a problem to map 2M even when the quicc engine is
not there ? Or should it check device tree instead ?

Christophe

\
 
 \ /
  Last update: 2019-09-14 18:52    [W:0.070 / U:1.812 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site