From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 05/33] drm/omap: partial workaround for DRA7 DMM errata i878
Date: Wed, 24 Feb 2016 11:14:15 +0200 [thread overview]
Message-ID: <56CD7467.60902@ti.com> (raw)
In-Reply-To: <5240664.Dy4C1HiFai@avalon>
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Hi,
On 23/02/16 23:57, Laurent Pinchart wrote:
> Hi Tomi,
>
> Thank you for the patch.
Thanks for review, good points. I'll drop this patch from the series for
now. The reason being, this issue is rather difficult to reproduce and
test, so any changes I do to patch this will take time to verify.
I'll address the comments later.
> On Friday 19 February 2016 11:47:40 Tomi Valkeinen wrote:
>> Errata i878 says that MPU should not be used to access RAM and DMM at
>> the same time. As it's not possible to prevent MPU accessing RAM, we
>> need to access DMM via a proxy.
>>
>> This patch changes DMM driver to access DMM registers via sDMA. Instead
>> of doing a normal readl/writel call to read/write a register, we use
>> sDMA to copy 4 bytes from/to the DMM registers.
>>
>> This patch provides only a partial workaround for i878, as not only DMM
>> register reads/writes are affected, but also accesses to the DMM mapped
>> buffers (framebuffers, usually).
>
> Will this patch really improve the situation if the DMM mapping is accessed
> anyway ?
Depends. For TI environments it helps, as we don't draw with the CPU. If
there's drawing done with CPU, the issue may still happen. I have never
seen it happen in normal situations, though, but I did manage to trigger
it with explicit stress testing.
Also, I don't have any good solution to the framebuffer part... Except
doing a memcpy, ruining the performance.
Tomi
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next prev parent reply other threads:[~2016-02-24 13:52 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-19 9:47 [PATCH 00/33] drm/omap: patches for v4.6 Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 01/33] drm/omap: HDMI: change enable/disable to avoid sync-losts Tomi Valkeinen
2016-02-23 10:22 ` Laurent Pinchart
2016-02-23 11:33 ` Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 02/33] HACK: drm/omap: always use blocking DMM fill Tomi Valkeinen
2016-02-23 10:27 ` Laurent Pinchart
2016-02-23 13:09 ` Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 03/33] HACK: drm/omap: fix memory barrier bug in DMM driver Tomi Valkeinen
2016-02-23 21:13 ` Laurent Pinchart
2016-02-24 10:34 ` Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 04/33] drm/omap: add dmm_read() and dmm_write() wrappers Tomi Valkeinen
2016-02-23 21:18 ` Laurent Pinchart
2016-02-19 9:47 ` [PATCH 05/33] drm/omap: partial workaround for DRA7 DMM errata i878 Tomi Valkeinen
2016-02-23 21:57 ` Laurent Pinchart
2016-02-24 9:14 ` Tomi Valkeinen [this message]
2017-09-29 12:29 ` Peter Ujfalusi
2016-02-19 9:47 ` [PATCH 06/33] drm/omap: drm_atomic_get_plane_state() may return ERR_PTR Tomi Valkeinen
2016-02-23 22:01 ` Laurent Pinchart
2016-02-19 9:47 ` [PATCH 07/33] drm/omap: tpd12s015: remove platform data support Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 08/33] drm/omap: tpd12s015: gpio descriptor API Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 09/33] drm/omap: tpd12s015: CT_CP_HPD as optional gpio Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 10/33] drm/omap: add define for DISPC_IRQ_WBUNCOMPLETEERROR Tomi Valkeinen
2016-02-23 22:04 ` Laurent Pinchart
2016-02-19 9:47 ` [PATCH 11/33] drm/omap: use dma_mapping_error in omap_gem_attach_pages Tomi Valkeinen
2016-02-23 22:10 ` Laurent Pinchart
2016-02-25 15:39 ` Tomi Valkeinen
2016-02-26 8:52 ` Laurent Pinchart
2016-02-26 9:07 ` Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 12/33] drm/omap: use dma_mapping_error in omap_gem_dma_sync Tomi Valkeinen
2016-02-23 22:14 ` Laurent Pinchart
2016-02-25 15:45 ` Tomi Valkeinen
2016-02-26 8:54 ` Laurent Pinchart
2016-02-19 9:47 ` [PATCH 13/33] drm/omap: print an error if display enable fails Tomi Valkeinen
2016-02-23 22:17 ` Laurent Pinchart
2016-02-19 9:47 ` [PATCH 14/33] drm/omap: gem: Clean up GEM objects memory flags Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 15/33] drm/omap: gem: Refactor GEM object allocation Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 16/33] drm/omap: gem: Implement dma_buf import Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 17/33] drm/omap: remove support for ext mem & sync Tomi Valkeinen
2016-02-23 22:42 ` Laurent Pinchart
2016-02-24 9:38 ` Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 18/33] drm/omap: increase vblank wait timeout Tomi Valkeinen
2016-02-23 22:43 ` Laurent Pinchart
2016-02-24 9:41 ` Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 19/33] drm/omap: DISPC: support double-pixel mode Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 20/33] drm/omap: support double-pixel Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 21/33] drm/omap: HDMI: support double-pixel pixel clock Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 22/33] drm/omap: HDMI: Fix HSW value Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 23/33] drm/omap: HDMI: fix WP timings for ilace Tomi Valkeinen
2016-02-19 9:47 ` [PATCH 24/33] drm/omap: DISPC: Fix field order for HDMI Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 25/33] drm/omap: HDMI5: Fix FC HSW value Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 26/33] drm/omap: HDMI5: clean up timings copy Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 27/33] drm/omap: HDMI5: Add interlace support Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 28/33] drm/omap: HDMI5: allow interlace Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 29/33] drm/omap: verify that display x-res is divisible by 8 Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 30/33] drm/omap: verify that fb plane pitches are the same Tomi Valkeinen
2016-02-23 23:02 ` Laurent Pinchart
2016-02-25 15:56 ` Tomi Valkeinen
2016-02-26 8:55 ` Laurent Pinchart
2016-02-26 9:12 ` Tomi Valkeinen
2016-02-26 9:27 ` Laurent Pinchart
2016-02-19 9:48 ` [PATCH 31/33] drm/omap: EBUSY status handling in omap_gem_fault() Tomi Valkeinen
2016-02-19 9:48 ` [PATCH 32/33] drm/omap: fix crtc->plane property delegation Tomi Valkeinen
2016-02-23 23:24 ` Laurent Pinchart
2016-02-19 9:48 ` [PATCH 33/33] drm/omap: check if rotation is supported before commit Tomi Valkeinen
2016-02-23 23:30 ` Laurent Pinchart
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