linux-kernel - Re: [PATCH v18 1/5] iommu/arm-smmu: Add pm

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Date:   Wed, 28 Nov 2018 08:32:58 -0600
From:   Thor Thayer <thor.thayer@...ux.intel.com>
To:     Vivek Gautam <vivek.gautam@...eaurora.org>, joro@...tes.org,
        robh+dt@...nel.org, robin.murphy@....com, will.deacon@....com,
        iommu@...ts.linux-foundation.org, devicetree@...r.kernel.org
Cc:     alex.williamson@...hat.com, mark.rutland@....com,
        rjw@...ysocki.net, robdclark@...il.com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, sboyd@...nel.org,
        tfiga@...omium.org, jcrouse@...eaurora.org,
        sricharan@...eaurora.org, m.szyprowski@...sung.com,
        architt@...eaurora.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v18 1/5] iommu/arm-smmu: Add pm_runtime/sleep ops

On 11/27/18 4:11 AM, Vivek Gautam wrote:
> From: Sricharan R <sricharan@...eaurora.org>
> 
> The smmu needs to be functional only when the respective
> master's using it are active. The device_link feature
> helps to track such functional dependencies, so that the
> iommu gets powered when the master device enables itself
> using pm_runtime. So by adapting the smmu driver for
> runtime pm, above said dependency can be addressed.
> 
> This patch adds the pm runtime/sleep callbacks to the
> driver and also the functions to parse the smmu clocks
> from DT and enable them in resume/suspend.
> We pull all the information about clocks from device tree.
> 
> Also, while we enable the runtime pm add a pm sleep suspend
> callback that pushes devices to low power state by turning
> the clocks off in a system sleep.
> Also add corresponding clock enable path in resume callback.
> 
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> Signed-off-by: Archit Taneja <architt@...eaurora.org>
> [Thor: Rework to get clocks from device tree]
> Signed-off-by: Thor Thayer <thor.thayer@...ux.intel.com>
> [vivek: rework for clock and pm ops]
> Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
> Reviewed-by: Tomasz Figa <tfiga@...omium.org>
> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Reviewed-by: Robin Murphy <robin.murphy@....com>
> ---
>   drivers/iommu/arm-smmu.c | 100 +++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 97 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index 5a28ae892504..e47c840fc6a8 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -44,10 +44,12 @@
>   #include <linux/module.h>
>   #include <linux/of.h>
>   #include <linux/of_address.h>
> +#include <linux/of_clk.h>
>   #include <linux/of_device.h>
>   #include <linux/of_iommu.h>
>   #include <linux/pci.h>
>   #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>   #include <linux/slab.h>
>   #include <linux/spinlock.h>
>  <snip>

Thanks! Tested the device tree clock portions on Intel SOCFPGA Stratix10 
DevKit.

Tested-by: Thor Thayer <thor.thayer@...ux.intel.com>