linux-kernel - Re: [PATCH v2 0/7] media: rkvdec: Add HEVC backend

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Message-ID: <25ce30446e8e8d038273fcdfb398c90995c242db.camel@collabora.com>
Date: Tue, 12 Aug 2025 14:26:41 -0400
From: Nicolas Dufresne <nicolas.dufresne@...labora.com>
To: Jonas Karlman <jonas@...boo.se>
Cc: Ezequiel Garcia <ezequiel@...guardiasur.com.ar>, Detlev Casanova	
 <detlev.casanova@...labora.com>, Mauro Carvalho Chehab
 <mchehab@...nel.org>,  Alex Bee <knaerzche@...il.com>,
 linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/7] media: rkvdec: Add HEVC backend

Hi Jonas,

Le mardi 12 août 2025 à 19:31 +0200, Jonas Karlman a écrit :
> On 8/12/2025 2:44 PM, Nicolas Dufresne wrote:
> > I forgot, 
> > 
> > Le mardi 12 août 2025 à 08:38 -0400, Nicolas Dufresne a écrit :
> > > > JCT-VC-HEVC_V1 on GStreamer-H.265-V4L2SL-Gst1.0:
> > > > 
> > > > - DBLK_D_VIXS_2 (fail)
> > > > - DSLICE_A_HHI_5 (fail)
> > > > - EXT_A_ericsson_4 (fail)
> > > > - PICSIZE_A_Bossen_1 (error)
> > > > - PICSIZE_B_Bossen_1 (error)
> > > > - PICSIZE_C_Bossen_1 (error)
> > > > - PICSIZE_D_Bossen_1 (error)
> > > > - SAODBLK_A_MainConcept_4 (fail)
> > > > - SAODBLK_B_MainConcept_4 (fail)
> > > > - TSUNEQBD_A_MAIN10_Technicolor_2 (error)
> > 
> > I'me getting the same result if I force a single job in fluster. The test I
> > posted was with 2 jobs. Detlev found that the iommu reset is required in
> > more
> > cases on RK3588/3576, perhaps the HEVC decoder in older hardware needs the
> > same,
> > I will try and report.
> 
> Vendor kernel [1] check following bits from RKVDEC_REG_INTERRUPT reg to
> decide if a full HW reset should be done.
> 
>   err_mask = RKVDEC_BUF_EMPTY_STA
>   	   | RKVDEC_BUS_STA
>   	   | RKVDEC_COLMV_REF_ERR_STA
>   	   | RKVDEC_ERR_STA
>   	   | RKVDEC_TIMEOUT_STA;
> 
> Adding proper reset support can be rather involved and main reason why
> this series does not handle it, better suited for a separate future
> series.
> 
> Proper HW reset will require e.g. dt-bindings, DT updates, pmu idle
> request integration and for rk3328 vendor even moved VPU reset to TF-A.
> 
> Doing the iommu detach/attach dance not only on RKVDEC_SOFTRESET_RDY
> could possible improve some cases, until full reset can be implemented.

Rockchip is following VSI design of "self reset" on error. But since the iommu
is part of the device, it also gets reset, which imply having to reprogram it.
This showed to be very reliable logic, despite RK doing a hard reset.

Since self reset is documented for RKVDEC_BUS_STA, RKVDEC_ERR_STA,
RKVDEC_TIMEOUT_STA, it would seem that RKVDEC_BUF_EMPTY_STA is redundant, unless
its asynchronous operation that need to be polled. Possibly something to
investigate. RKVDEC_BUF_EMPTY_STA and RKVDEC_COLMV_REF_ERR_STA are not
documented a such, so its not quite logical to reprogram the iommu.

I don't immediately trust reference software for these type of things, we should
find what works best and have a rationale for. The hard reset is every
expensive, and hard to upstream.

Nicolas

> 
> [1]
> https://github.com/Kwiboo/linux-rockchip/blob/linux-6.1-stan-rkr6.1/drivers/video/rockchip/mpp/mpp_rkvdec.c#L924-L931
> 
> Regards,
> Jonas
> 
> > 
> > Nicolas

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