Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-20 Thread Greg KH
On Fri, Mar 17, 2023 at 09:07:50PM -0700, John Harrison wrote: > On 3/17/2023 05:58, Greg KH wrote: > > On Thu, Mar 16, 2023 at 01:58:35PM -0700, John Harrison wrote: > > > On 3/15/2023 10:57, Greg KH wrote: > > > > On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: > > > > > On

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-17 Thread John Harrison
On 3/17/2023 05:58, Greg KH wrote: On Thu, Mar 16, 2023 at 01:58:35PM -0700, John Harrison wrote: On 3/15/2023 10:57, Greg KH wrote: On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: On 3/15/2023 00:51, Greg KH wrote: On Mon, Mar 13, 2023 at 07:22:11PM -0700,

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-17 Thread Jason Andryuk
On Fri, Mar 17, 2023 at 8:58 AM Greg KH wrote: > > On Thu, Mar 16, 2023 at 01:58:35PM -0700, John Harrison wrote: > > On 3/15/2023 10:57, Greg KH wrote: > > > On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: > > > > On 3/15/2023 00:51, Greg KH wrote: > > > > > On Mon, Mar 13, 2023

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-17 Thread Greg KH
On Thu, Mar 16, 2023 at 01:58:35PM -0700, John Harrison wrote: > On 3/15/2023 10:57, Greg KH wrote: > > On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: > > > On 3/15/2023 00:51, Greg KH wrote: > > > > On Mon, Mar 13, 2023 at 07:22:11PM -0700, john.c.harri...@intel.com > > > >

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-16 Thread John Harrison
On 3/15/2023 10:57, Greg KH wrote: On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: On 3/15/2023 00:51, Greg KH wrote: On Mon, Mar 13, 2023 at 07:22:11PM -0700, john.c.harri...@intel.com wrote: From: John Harrison Direction from hardware is that ring buffers should never be

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-15 Thread Greg KH
On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: > On 3/15/2023 00:51, Greg KH wrote: > > On Mon, Mar 13, 2023 at 07:22:11PM -0700, john.c.harri...@intel.com wrote: > > > From: John Harrison > > > > > > Direction from hardware is that ring buffers should never be mapped > > > via

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-15 Thread John Harrison
On 3/15/2023 00:51, Greg KH wrote: On Mon, Mar 13, 2023 at 07:22:11PM -0700, john.c.harri...@intel.com wrote: From: John Harrison Direction from hardware is that ring buffers should never be mapped via the BAR on systems with LLC. There are too many caching pitfalls due to the way BAR

Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-15 Thread Greg KH
On Mon, Mar 13, 2023 at 07:22:11PM -0700, john.c.harri...@intel.com wrote: > From: John Harrison > > Direction from hardware is that ring buffers should never be mapped > via the BAR on systems with LLC. There are too many caching pitfalls > due to the way BAR accesses are routed. So it is

[Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC

2023-03-13 Thread John . C . Harrison
From: John Harrison Direction from hardware is that ring buffers should never be mapped via the BAR on systems with LLC. There are too many caching pitfalls due to the way BAR accesses are routed. So it is safest to just not use it. Signed-off-by: John Harrison Fixes: 9d80841ea4c9 ("drm/i915: