[PATCH 9/9] drm/ttm: Sanity check mapping attributes on powerpc in ttm_io_prot()
On Thu, 2014-09-04 at 16:52 +0900, Michel D?nzer wrote:
> > #endif
> > +#if defined(__powerpc__) && !defined(CONFIG_NOT_COHERENT_CACHE)
> > + /*
> > + * Using a non-cachable mapping of system memory on
> > + * cache coherent powerpc's can be fatal, let's make
> > + * sure this doesn't happen and warn if it does. The
> > + * only exception is powermac with AGP which has to
> > + * take the risk.
> > + */
> > + if (!machine_is(powermac) &&
> > + ((caching_flags & TTM_PL_FLAG_SYSTEM) ||
> > + (caching_flags & TTM_PL_FLAG_TT))) {
> > + pr_err_once("TTM: Attempt to use a non-cached"
> > + " mapping on RAM unsupported !\n");
> > + return tmp;
>
> NAK, this breaks AGP on PowerMacs.
No it doesn't :-)
Cheers,
Ben.
[PATCH 9/9] drm/ttm: Sanity check mapping attributes on powerpc in ttm_io_prot()
On 04.09.2014 18:34, Benjamin Herrenschmidt wrote:
> On Thu, 2014-09-04 at 16:52 +0900, Michel D?nzer wrote:
>>>#endif
>>> +#if defined(__powerpc__) && !defined(CONFIG_NOT_COHERENT_CACHE)
>>> + /*
>>> + * Using a non-cachable mapping of system memory on
>>> + * cache coherent powerpc's can be fatal, let's make
>>> + * sure this doesn't happen and warn if it does. The
>>> + * only exception is powermac with AGP which has to
>>> + * take the risk.
>>> + */
>>> + if (!machine_is(powermac) &&
>>> + ((caching_flags & TTM_PL_FLAG_SYSTEM) ||
>>> + (caching_flags & TTM_PL_FLAG_TT))) {
>>> + pr_err_once("TTM: Attempt to use a non-cached"
>>> + " mapping on RAM unsupported !\n");
>>> + return tmp;
>>
>> NAK, this breaks AGP on PowerMacs.
>
> No it doesn't :-)
Yeah sorry, I was blind.
--
Earthling Michel D?nzer| http://www.amd.com
Libre software enthusiast |Mesa and X developer
[PATCH 9/9] drm/ttm: Sanity check mapping attributes on powerpc in ttm_io_prot()
On all current cache coherent powerpc processors, it is not legit
to map system memory non-cachable. This will cause aliases with
the linear mapping which can be fatal.
The TTM should generally avoid it after Jerome placement patches but
let's add a sanity check anyway to catch any possible remaining issue.
Signed-off-by: Benjamin Herrenschmidt
---
drivers/gpu/drm/ttm/ttm_bo_util.c | 17 +
1 file changed, 17 insertions(+)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c
b/drivers/gpu/drm/ttm/ttm_bo_util.c
index ef2ac3c..48095be 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -37,6 +37,9 @@
#include
#include
#include
+#if defined(__powerpc__)
+#include
+#endif
void ttm_bo_free_old_node(struct ttm_buffer_object *bo)
{
@@ -498,6 +501,20 @@ pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t tmp)
tmp = pgprot_noncached(tmp);
#endif
+#if defined(__powerpc__) && !defined(CONFIG_NOT_COHERENT_CACHE)
+ /*
+* Using a non-cachable mapping of system memory on
+* cache coherent powerpc's can be fatal, let's make
+* sure this doesn't happen and warn if it does. The
+* only exception is powermac with AGP which has to
+* take the risk.
+*/
+ if (!machine_is(powermac) &&
+ ((caching_flags & TTM_PL_FLAG_SYSTEM) ||
+(caching_flags & TTM_PL_FLAG_TT))) {
+ pr_err_once("TTM: Attempt to use a non-cached"
+ " mapping on RAM unsupported !\n");
+ return tmp;
}
#endif
#if defined(__ia64__) || defined(__arm__) || defined(__powerpc__)
[PATCH 9/9] drm/ttm: Sanity check mapping attributes on powerpc in ttm_io_prot()
On 04.09.2014 16:47, Benjamin Herrenschmidt wrote:
> On all current cache coherent powerpc processors, it is not legit
> to map system memory non-cachable. This will cause aliases with
> the linear mapping which can be fatal.
>
> The TTM should generally avoid it after Jerome placement patches but
> let's add a sanity check anyway to catch any possible remaining issue.
>
> Signed-off-by: Benjamin Herrenschmidt
[...]
> @@ -498,6 +501,20 @@ pgprot_t ttm_io_prot(uint32_t caching_flags, pgprot_t
> tmp)
> tmp = pgprot_noncached(tmp);
>
> #endif
> +#if defined(__powerpc__) && !defined(CONFIG_NOT_COHERENT_CACHE)
> + /*
> + * Using a non-cachable mapping of system memory on
> + * cache coherent powerpc's can be fatal, let's make
> + * sure this doesn't happen and warn if it does. The
> + * only exception is powermac with AGP which has to
> + * take the risk.
> + */
> + if (!machine_is(powermac) &&
> + ((caching_flags & TTM_PL_FLAG_SYSTEM) ||
> + (caching_flags & TTM_PL_FLAG_TT))) {
> + pr_err_once("TTM: Attempt to use a non-cached"
> + " mapping on RAM unsupported !\n");
> + return tmp;
NAK, this breaks AGP on PowerMacs.
--
Earthling Michel D?nzer| http://www.amd.com
Libre software enthusiast |Mesa and X developer
