Re: DMA-buf and uncached system memory

2021-02-16 Thread Daniel Vetter
On Mon, Feb 15, 2021 at 09:58:08AM +0100, Christian König wrote: > Hi guys, > > we are currently working an Freesync and direct scan out from system memory > on AMD APUs in A+A laptops. > > On problem we stumbled over is that our display hardware needs to scan out > from uncached system memory

Re: DMA-buf and uncached system memory

2021-02-15 Thread Nicolas Dufresne
Le lundi 15 février 2021 à 13:10 +0100, Christian König a écrit : > > > Am 15.02.21 um 13:00 schrieb Thomas Zimmermann: > > Hi > > > > Am 15.02.21 um 10:49 schrieb Thomas Zimmermann: > > > Hi > > > > > > Am 15.02.21 um 09:58 schrieb Christian König: > > > > Hi guys, > > > > > > > > we are

Re: DMA-buf and uncached system memory

2021-02-15 Thread Nicolas Dufresne
Le lundi 15 février 2021 à 09:58 +0100, Christian König a écrit : > Hi guys, > > we are currently working an Freesync and direct scan out from system > memory on AMD APUs in A+A laptops. > > On problem we stumbled over is that our display hardware needs to scan > out from uncached system

Re: [Linaro-mm-sig] DMA-buf and uncached system memory

2021-02-15 Thread Christian König
Am 15.02.21 um 15:41 schrieb David Laight: From: Christian König Sent: 15 February 2021 12:05 ... Snooping the CPU caches introduces some extra latency, so what can happen is that the response to the PCIe read comes to late for the scanout. The result is an underflow and flickering

RE: DMA-buf and uncached system memory

2021-02-15 Thread David Laight
From: Christian König > Sent: 15 February 2021 12:05 ... > Snooping the CPU caches introduces some extra latency, so what can > happen is that the response to the PCIe read comes to late for the > scanout. The result is an underflow and flickering whenever something is > in the cache which needs

Re: DMA-buf and uncached system memory

2021-02-15 Thread Christian König
Am 15.02.21 um 13:16 schrieb Lucas Stach: [SNIP] Userspace components can then of course tell the exporter what the importer needs, but validation if that stuff is correct and doesn't crash the system must happen in the kernel. What exactly do you mean by "scanout requires non-coherent

Re: DMA-buf and uncached system memory

2021-02-15 Thread Lucas Stach
Am Montag, dem 15.02.2021 um 13:04 +0100 schrieb Christian König: > Am 15.02.21 um 12:53 schrieb Lucas Stach: > > Am Montag, dem 15.02.2021 um 10:34 +0100 schrieb Christian König: > > > Am 15.02.21 um 10:06 schrieb Simon Ser: > > > > On Monday, February 15th, 2021 at 9:58 AM, Christian König > >

Re: DMA-buf and uncached system memory

2021-02-15 Thread Christian König
Am 15.02.21 um 13:00 schrieb Thomas Zimmermann: Hi Am 15.02.21 um 10:49 schrieb Thomas Zimmermann: Hi Am 15.02.21 um 09:58 schrieb Christian König: Hi guys, we are currently working an Freesync and direct scan out from system memory on AMD APUs in A+A laptops. On problem we stumbled

Re: DMA-buf and uncached system memory

2021-02-15 Thread Christian König
Am 15.02.21 um 12:53 schrieb Lucas Stach: Am Montag, dem 15.02.2021 um 10:34 +0100 schrieb Christian König: Am 15.02.21 um 10:06 schrieb Simon Ser: On Monday, February 15th, 2021 at 9:58 AM, Christian König wrote: we are currently working an Freesync and direct scan out from system memory

Re: DMA-buf and uncached system memory

2021-02-15 Thread Thomas Zimmermann
Hi Am 15.02.21 um 10:49 schrieb Thomas Zimmermann: Hi Am 15.02.21 um 09:58 schrieb Christian König: Hi guys, we are currently working an Freesync and direct scan out from system memory on AMD APUs in A+A laptops. On problem we stumbled over is that our display hardware needs to scan out

Re: DMA-buf and uncached system memory

2021-02-15 Thread Lucas Stach
Am Montag, dem 15.02.2021 um 10:34 +0100 schrieb Christian König: > > Am 15.02.21 um 10:06 schrieb Simon Ser: > > On Monday, February 15th, 2021 at 9:58 AM, Christian König > > wrote: > > > > > we are currently working an Freesync and direct scan out from system > > > memory on AMD APUs in A+A

Re: DMA-buf and uncached system memory

2021-02-15 Thread Thomas Zimmermann
Hi Am 15.02.21 um 09:58 schrieb Christian König: Hi guys, we are currently working an Freesync and direct scan out from system memory on AMD APUs in A+A laptops. On problem we stumbled over is that our display hardware needs to scan out from uncached system memory and we currently don't

Re: DMA-buf and uncached system memory

2021-02-15 Thread Christian König
Am 15.02.21 um 10:06 schrieb Simon Ser: On Monday, February 15th, 2021 at 9:58 AM, Christian König wrote: we are currently working an Freesync and direct scan out from system memory on AMD APUs in A+A laptops. On problem we stumbled over is that our display hardware needs to scan out

Re: DMA-buf and uncached system memory

2021-02-15 Thread Simon Ser
On Monday, February 15th, 2021 at 9:58 AM, Christian König wrote: > we are currently working an Freesync and direct scan out from system > memory on AMD APUs in A+A laptops. > > On problem we stumbled over is that our display hardware needs to scan > out from uncached system memory and we

DMA-buf and uncached system memory

2021-02-15 Thread Christian König
Hi guys, we are currently working an Freesync and direct scan out from system memory on AMD APUs in A+A laptops. On problem we stumbled over is that our display hardware needs to scan out from uncached system memory and we currently don't have a way to communicate that through DMA-buf.