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Mon, 29 Dec 2025 04:07:26 -0600 Received: from [172.24.233.149] (ws.dhcp.ti.com [172.24.233.149]) by lelvem-mr06.itg.ti.com (8.18.1/8.18.1) with ESMTP id 5BTA7KOP3220205; Mon, 29 Dec 2025 04:07:21 -0600 Message-ID: Date: Mon, 29 Dec 2025 15:37:20 +0530 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 17/18] media: ti: j721e-csi2rx: Support runtime suspend To: Jai Luthra , Tomi Valkeinen , , , , "Vignesh Raghavendra" CC: , , , , , , , , , , , , , , , , , References: <20251112115459.2479225-1-r-donadkar@ti.com> <20251112115459.2479225-18-r-donadkar@ti.com> <032b441e-eefc-4574-bf7a-5c4d09599925@ideasonboard.com> <176517937821.20066.4604793543801654609@freya> Content-Language: en-US From: Rishikesh Donadkar In-Reply-To: <176517937821.20066.4604793543801654609@freya> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-C2ProcessedOrg: 333ef613-75bf-4e12-a4b1-8e3623f5dcea X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PEPF000066EA:EE_|CO1PR10MB4466:EE_ X-MS-Office365-Filtering-Correlation-Id: e8ae8116-8be8-462b-0dec-08de46c2159d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|7416014|36860700013|1800799024; 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X-OriginatorOrg: ti.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Dec 2025 10:07:33.2623 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e8ae8116-8be8-462b-0dec-08de46c2159d X-MS-Exchange-CrossTenant-Id: e5b49634-450b-4709-8abb-1e2b19b982b7 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=e5b49634-450b-4709-8abb-1e2b19b982b7;Ip=[198.47.21.195];Helo=[flwvzet201.ext.ti.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000066EA.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO1PR10MB4466 On 08/12/25 13:06, Jai Luthra wrote: > Hi Tomi, Hi Jai, Tomi, > > Quoting Tomi Valkeinen (2025-12-01 18:52:36) >> Hi, >> >> On 12/11/2025 13:54, Rishikesh Donadkar wrote: >>> From: Jai Luthra >>> >>> Add support for runtime power-management to enable powering off the >>> shared power domain between Cadence CSI2RX and TI CSI2RX wrapper when >>> the device(s) are not in use. >>> >>> When powering off the IP, the PSI-L endpoint loses the paired DMA >>> channels. Thus we have to release the DMA channels at runtime suspend >>> and request them again at resume. >> I'm not an expert on the dmaengine, but to me this sounds like a bug in >> the dma driver. It just sounds very wrong... >> > Cc: Vignesh > > IIRC this was done because on AM62 the CSI2RX is on a separate power domain > and it uses DMA channels from the system-wide DMA engine. > > And as those two drivers have different set of users, we have situations > where CSI2RX goes to runtime suspend state and turns off the power and > clocks, while the DMA engine remains on as it has other users. This leads > to the paired PSIL channels to become invalid, and needs a re-pairing. > > I am not an expert on DMA engine APIs to know how feasible it would be to > do the book-keeping of the power state of various devices in the DMA driver > and manage the re-pairing entirely there. > > On AM62A and later devices, there is a dedicated instance of the BCDMA > engine for camera pipeline on the same power domain as CSI2RX, so this is > not a problem. Rishikesh/Vignesh please correct me if I'm wrong, as it has > been a while since I looked at this in depth. > > >>> Tested-by: Rishikesh Donadkar >>> Reviewed-by: Rishikesh Donadkar >>> Signed-off-by: Jai Luthra >>> Signed-off-by: Rishikesh Donadkar >>> --- >>> drivers/media/platform/ti/Kconfig | 1 + >>> .../platform/ti/j721e-csi2rx/j721e-csi2rx.c | 55 ++++++++++++++++++- >>> 2 files changed, 54 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/media/platform/ti/Kconfig b/drivers/media/platform/ti/Kconfig >>> index 3bc4aa35887e6..a808063e24779 100644 >>> --- a/drivers/media/platform/ti/Kconfig >>> +++ b/drivers/media/platform/ti/Kconfig >>> @@ -70,6 +70,7 @@ config VIDEO_TI_J721E_CSI2RX >>> depends on VIDEO_CADENCE_CSI2RX >>> depends on PHY_CADENCE_DPHY_RX || COMPILE_TEST >>> depends on ARCH_K3 || COMPILE_TEST >>> + depends on PM >>> select VIDEOBUF2_DMA_CONTIG >>> select V4L2_FWNODE >>> help >>> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c >>> index 528041ee78cf3..21e032c64b901 100644 >>> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c >>> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c >>> @@ -13,6 +13,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include >>> >>> #include >>> @@ -963,12 +964,16 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count) >>> unsigned long flags; >>> int ret = 0; >>> >>> + ret = pm_runtime_resume_and_get(csi->dev); >>> + if (ret) >>> + return ret; >>> + >>> spin_lock_irqsave(&dma->lock, flags); >>> if (list_empty(&dma->queue)) >>> ret = -EIO; >>> spin_unlock_irqrestore(&dma->lock, flags); >>> if (ret) >>> - return ret; >>> + goto err; >>> >>> ret = video_device_pipeline_start(&ctx->vdev, &csi->pipe); >>> if (ret) >>> @@ -1024,6 +1029,8 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count) >>> writel(0, csi->shim + SHIM_DMACNTX(ctx->idx)); >>> err: >>> ti_csi2rx_cleanup_buffers(ctx, VB2_BUF_STATE_QUEUED); >>> + pm_runtime_put(csi->dev); >>> + >>> return ret; >>> } >>> >>> @@ -1055,6 +1062,7 @@ static void ti_csi2rx_stop_streaming(struct vb2_queue *vq) >>> >>> ti_csi2rx_stop_dma(ctx); >>> ti_csi2rx_cleanup_buffers(ctx, VB2_BUF_STATE_ERROR); >>> + pm_runtime_put(csi->dev); >>> } >>> >>> static const struct vb2_ops csi_vb2_qops = { >>> @@ -1261,7 +1269,9 @@ static void ti_csi2rx_cleanup_notifier(struct ti_csi2rx_dev *csi) >>> >>> static void ti_csi2rx_cleanup_ctx(struct ti_csi2rx_ctx *ctx) >>> { >>> - dma_release_channel(ctx->dma.chan); >>> + if (!pm_runtime_status_suspended(ctx->csi->dev)) >>> + dma_release_channel(ctx->dma.chan); >>> + >>> vb2_queue_release(&ctx->vidq); >>> >>> video_unregister_device(&ctx->vdev); >>> @@ -1512,6 +1522,39 @@ static int ti_csi2rx_init_ctx(struct ti_csi2rx_ctx *ctx) >>> return ret; >>> } >>> >>> +static int ti_csi2rx_runtime_suspend(struct device *dev) >>> +{ >>> + struct ti_csi2rx_dev *csi = dev_get_drvdata(dev); >>> + int i; >>> + >>> + if (csi->enable_count != 0) >>> + return -EBUSY; >>> + >>> + for (i = 0; i < csi->num_ctx; i++) >>> + dma_release_channel(csi->ctx[i].dma.chan); >>> + >>> + return 0; >>> +} >>> + >>> +static int ti_csi2rx_runtime_resume(struct device *dev) >>> +{ >>> + struct ti_csi2rx_dev *csi = dev_get_drvdata(dev); >>> + int ret, i; >>> + >>> + for (i = 0; i < csi->num_ctx; i++) { >>> + ret = ti_csi2rx_init_dma(&csi->ctx[i]); >> If runtime_resume always requests the dma channels, is the call to >> ti_csi2rx_init_dma() in ti_csi2rx_init_ctx() needed? If not, you could >> inline the code from ti_csi2rx_init_dma() to here and also drop the >> dma_release_channel() call from ti_csi2rx_cleanup_ctx(), making the flow >> more understandable. >> > Makes sense. > >>> + if (ret) >>> + return ret; >>> + } >>> + >>> + return 0; >>> +} >>> + >>> +static const struct dev_pm_ops ti_csi2rx_pm_ops = { >>> + RUNTIME_PM_OPS(ti_csi2rx_runtime_suspend, ti_csi2rx_runtime_resume, >>> + NULL) >>> +}; >>> + >>> static int ti_csi2rx_probe(struct platform_device *pdev) >>> { >>> struct device_node *np = pdev->dev.of_node; >>> @@ -1579,6 +1622,10 @@ static int ti_csi2rx_probe(struct platform_device *pdev) >>> goto err_notifier; >>> } >>> >>> + pm_runtime_set_active(csi->dev); >>> + pm_runtime_enable(csi->dev); >>> + pm_request_idle(csi->dev); >> I always forget what exactly the runtime_pm funcs do. What's the idea >> here? If you do something else than the plain standard >> pm_runtime_enable(), I think it's good to mention what/why in a comment. >> > https://docs.kernel.org/power/runtime_pm.html#runtime-pm-initialization-device-probing-and-removal > > The pm_request_idle() is done to queue up a job to suspend the hardware > until userspace starts streaming, to save power. > > The runtime_set_active() is used because the power domain for CSI is by > default turned on when system boots up. But Rishikesh, please double check > that before v9 on AM62. I checked with AM62 when booting up, with CSI drivers being probed/not probed. The device state was OFF by default on boot in both cases. So, plain pm_runtime_enable() should work. That will simplify the dma_request/release_chan() calls  in the runtime suspend/resume flow. Thanks & Regards, Rishikesh > >>> return 0; >>> >>> err_notifier: >>> @@ -1609,6 +1656,9 @@ static void ti_csi2rx_remove(struct platform_device *pdev) >>> mutex_destroy(&csi->mutex); >>> dma_free_coherent(csi->dev, csi->drain.len, csi->drain.vaddr, >>> csi->drain.paddr); >>> + pm_runtime_disable(&pdev->dev); >>> + pm_runtime_set_suspended(&pdev->dev); >>> + >>> } >>> >>> static const struct of_device_id ti_csi2rx_of_match[] = { >>> @@ -1623,6 +1673,7 @@ static struct platform_driver ti_csi2rx_pdrv = { >>> .driver = { >>> .name = TI_CSI2RX_MODULE_NAME, >>> .of_match_table = ti_csi2rx_of_match, >>> + .pm = &ti_csi2rx_pm_ops, >>> }, >>> }; >>>