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From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 02/33] HACK: drm/omap: always use blocking DMM fill
Date: Tue, 23 Feb 2016 15:09:58 +0200	[thread overview]
Message-ID: <56CC5A26.3090200@ti.com> (raw)
In-Reply-To: <1818041.Py0QKdZPaW@avalon>


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On 23/02/16 12:27, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Friday 19 February 2016 11:47:37 Tomi Valkeinen wrote:
>> The current driver uses non-blocking DMM fill when releasing memory.
>> This gives us a small performance increase as we don't have to wait for
>> the fill operation to finish.
>>
>> However, the driver does not have any error handling for non-blocking
>> fill. In case of an error, the fill operation may silently fail, leading
>> to leaking DMM engines, which may eventually lead to deadlock if we run
>> out of DMM engines.
>>
>> This patch makes the DMM driver always use blocking fills, so that we
>> can catch the errors. A more complex option would be to allow
>> non-blocking fills, and implement proper error handling, but that is
>> left for the future.
>>
>> This patch is a HACK, as the proper fix is to either decide to always
>> use sync fills and remove all the async related code, or fix the async
>> code.
> 
> Could you capture this in the comment in the source code below ? I'd also 
> replace XXXX with either FIXME or TODO.

Yes, the comment was a bit lacking. Here's an updated comment:

/*
 * FIXME
 *
 * Asynchronous fill does not work reliably, as the driver does not
 * handle errors in the async code paths. The fill operation may
 * silently fail, leading to leaking DMM engines, which may eventually
 * lead to deadlock if we run out of DMM engines.
 *
 * For now, always set 'wait' so that we only use sync fills. Async
 * fills should be fixed, or alternatively we could decide to only
 * support sync fills and so the whole async code path could be removed.
 */

 Tomi


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  reply	other threads:[~2016-02-23 13:10 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 [this message]
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
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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