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[2/2] arm: socfpga: Set share override bit of the l2 cache controller

Message ID 1416546280-12068-2-git-send-email-dinguyen@opensource.altera.com (mailing list archive)
State New, archived
Headers show

Commit Message

dinguyen@opensource.altera.com Nov. 21, 2014, 5:04 a.m. UTC 
From: Dinh Nguyen <dinguyen@opensource.altera.com>

By not having bit 22 set in the PL310 Auxiliary Control register (shared
attribute override enable) has the side effect of transforming Normal
Shared Non-cacheable reads into Cacheable no-allocate reads.

Coherent DMA buffers in Linux always have a Cacheable alias via the
kernel linear mapping and the processor can speculatively load cache
lines into the PL310 controller. With bit 22 cleared, Non-cacheable
reads would unexpectedly hit such cache lines leading to buffer
corruption.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
---
 arch/arm/mach-socfpga/socfpga.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Arnd Bergmann Nov. 21, 2014, 11:04 a.m. UTC | #1 
On Thursday 20 November 2014 23:04:40 dinguyen@opensource.altera.com wrote:
> 
> ---
>  arch/arm/mach-socfpga/socfpga.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
> index 13b1858..afc009f 100644
> --- a/arch/arm/mach-socfpga/socfpga.c
> +++ b/arch/arm/mach-socfpga/socfpga.c
> @@ -105,7 +105,8 @@ static const char *altera_dt_match[] = {
>  
>  DT_MACHINE_START(SOCFPGA, "Altera SOCFPGA")
>         .l2c_aux_val    = L310_AUX_CTRL_DATA_PREFETCH |
> -                         L310_AUX_CTRL_INSTR_PREFETCH,
> +                         L310_AUX_CTRL_INSTR_PREFETCH |
> +                         L2C_AUX_CTRL_SHARED_OVERRIDE,
>         .l2c_aux_mask   = ~0,
>         .smp            = smp_ops(socfpga_smp_ops),
>         .map_io         = socfpga_map_io,

Hi Dinh,

Please do this by putting the appropriate proterties into the
l2x0 DT node instead.

	Arnd
dinguyen@opensource.altera.com Nov. 21, 2014, 3:27 p.m. UTC | #2 
Hi Arnd,

On 11/21/14, 5:04 AM, Arnd Bergmann wrote:
> On Thursday 20 November 2014 23:04:40 dinguyen@opensource.altera.com wrote:
>>
>> ---
>>  arch/arm/mach-socfpga/socfpga.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
>> index 13b1858..afc009f 100644
>> --- a/arch/arm/mach-socfpga/socfpga.c
>> +++ b/arch/arm/mach-socfpga/socfpga.c
>> @@ -105,7 +105,8 @@ static const char *altera_dt_match[] = {
>>  
>>  DT_MACHINE_START(SOCFPGA, "Altera SOCFPGA")
>>         .l2c_aux_val    = L310_AUX_CTRL_DATA_PREFETCH |
>> -                         L310_AUX_CTRL_INSTR_PREFETCH,
>> +                         L310_AUX_CTRL_INSTR_PREFETCH |
>> +                         L2C_AUX_CTRL_SHARED_OVERRIDE,
>>         .l2c_aux_mask   = ~0,
>>         .smp            = smp_ops(socfpga_smp_ops),
>>         .map_io         = socfpga_map_io,
> 
> Hi Dinh,
> 
> Please do this by putting the appropriate proterties into the
> l2x0 DT node instead.
> 

I don't see a way to do this yet in DT. Perhaps I'm missing a patchset
to allow this?

Thanks,
Dinh
Dinh Nguyen Dec. 17, 2014, 7:46 p.m. UTC | #3 
Hi Arnd,

On 11/21/14, 5:04 AM, Arnd Bergmann wrote:
> On Thursday 20 November 2014 23:04:40 dinguyen@opensource.altera.com wrote:
>>
>> ---
>>  arch/arm/mach-socfpga/socfpga.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
>> index 13b1858..afc009f 100644
>> --- a/arch/arm/mach-socfpga/socfpga.c
>> +++ b/arch/arm/mach-socfpga/socfpga.c
>> @@ -105,7 +105,8 @@ static const char *altera_dt_match[] = {
>>  
>>  DT_MACHINE_START(SOCFPGA, "Altera SOCFPGA")
>>         .l2c_aux_val    = L310_AUX_CTRL_DATA_PREFETCH |
>> -                         L310_AUX_CTRL_INSTR_PREFETCH,
>> +                         L310_AUX_CTRL_INSTR_PREFETCH |
>> +                         L2C_AUX_CTRL_SHARED_OVERRIDE,
>>         .l2c_aux_mask   = ~0,
>>         .smp            = smp_ops(socfpga_smp_ops),
>>         .map_io         = socfpga_map_io,
> 
> Hi Dinh,
> 
> Please do this by putting the appropriate proterties into the
> l2x0 DT node instead.
> 

I don't see a way to do this using the l2x0 DT node.

Thanks,
Dinh
diff mbox

Patch

diff --git a/arch/arm/mach-socfpga/socfpga.c b/arch/arm/mach-socfpga/socfpga.c
index 13b1858..afc009f 100644
--- a/arch/arm/mach-socfpga/socfpga.c
+++ b/arch/arm/mach-socfpga/socfpga.c
@@ -105,7 +105,8 @@  static const char *altera_dt_match[] = {
 
 DT_MACHINE_START(SOCFPGA, "Altera SOCFPGA")
 	.l2c_aux_val	= L310_AUX_CTRL_DATA_PREFETCH |
-			  L310_AUX_CTRL_INSTR_PREFETCH,
+			  L310_AUX_CTRL_INSTR_PREFETCH |
+			  L2C_AUX_CTRL_SHARED_OVERRIDE,
 	.l2c_aux_mask	= ~0,
 	.smp		= smp_ops(socfpga_smp_ops),
 	.map_io		= socfpga_map_io,