linux-hardening - Re: [PATCH 05/12] dmaengine: Add STM32 DMA3 support

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Message-ID: <38193848-597d-47c1-9aea-5357e58f9983@wanadoo.fr>
Date: Sat, 4 May 2024 16:27:53 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: amelie.delaunay@...s.st.com
Cc: alexandre.torgue@...s.st.com, conor+dt@...nel.org,
 devicetree@...r.kernel.org, dmaengine@...r.kernel.org,
 krzysztof.kozlowski+dt@...aro.org, linux-arm-kernel@...ts.infradead.org,
 linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-stm32@...md-mailman.stormreply.com, mcoquelin.stm32@...il.com,
 robh+dt@...nel.org, vkoul@...nel.org
Subject: Re: [PATCH 05/12] dmaengine: Add STM32 DMA3 support

Le 23/04/2024 à 14:32, Amelie Delaunay a écrit :
> STM32 DMA3 driver supports the 3 hardware configurations of the STM32 DMA3
> controller:
> - LPDMA (Low Power): 4 channels, no FIFO
> - GPDMA (General Purpose): 16 channels, FIFO from 8 to 32 bytes
> - HPDMA (High Performance): 16 channels, FIFO from 8 to 256 bytes
> Hardware configuration of the channels is retrieved from the hardware
> configuration registers.
> The client can specify its channel requirements through device tree.
> STM32 DMA3 channels can be individually reserved either because they are
> secure, or dedicated to another CPU.
> Indeed, channels availability depends on Resource Isolation Framework
> (RIF) configuration. RIF grants access to buses with Compartiment ID
> (CIF) filtering, secure and privilege level. It also assigns DMA channels
> to one or several processors.
> DMA channels used by Linux should be CID-filtered and statically assigned
> to CID1 or shared with other CPUs but using semaphore. In case CID
> filtering is not configured, dma-channel-mask property can be used to
> specify available DMA channels to the kernel, otherwise such channels
> will be marked as reserved and can't be used by Linux.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay-rj0Iel/JR4NBDgjK7y7TUQ@...lic.gmane.org>
> ---

...

> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +	pm_runtime_get_noresume(&pdev->dev);
> +	pm_runtime_put(&pdev->dev);
> +
> +	dev_info(&pdev->dev, "STM32 DMA3 registered rev:%lu.%lu\n",
> +		 FIELD_GET(VERR_MAJREV, verr), FIELD_GET(VERR_MINREV, verr));
> +
> +	return 0;
> +
> +err_clk_disable:
> +	clk_disable_unprepare(ddata->clk);
> +
> +	return ret;
> +}
> +
> +static void stm32_dma3_remove(struct platform_device *pdev)
> +{
> +	pm_runtime_disable(&pdev->dev);

Hi,

missing clk_disable_unprepare(ddata->clk);?

as in the error handling path on the probe just above?

CJ

> +}

...