linux-kernel - Re: [PATCH v6 3/4] venus: firmware: add no TZ boot and shutdown routine

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Date:   Mon, 27 Aug 2018 12:06:14 +0900
From:   Alexandre Courbot <acourbot@...omium.org>
To:     vgarodia@...eaurora.org
Cc:     Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>, robh@...nel.org,
        mark.rutland@....com, Andy Gross <andy.gross@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, bjorn.andersson@...aro.org,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v6 3/4] venus: firmware: add no TZ boot and shutdown routine

On Fri, Aug 24, 2018 at 9:26 PM Vikash Garodia <vgarodia@...eaurora.org> wrote:
>
> Hi Alex,
>
> On 2018-08-24 13:09, Alexandre Courbot wrote:
> > On Thu, Aug 23, 2018 at 11:29 PM Vikash Garodia
> > <vgarodia@...eaurora.org> wrote:
>
> [snip]
>
> >> +struct video_firmware {
> >> +       struct device *dev;
> >> +       struct iommu_domain *iommu_domain;
> >> +};
> >> +
> >>  /**
> >>   * struct venus_core - holds core parameters valid for all instances
> >>   *
> >> @@ -98,6 +103,7 @@ struct venus_caps {
> >>   * @dev:               convenience struct device pointer
> >>   * @dev_dec:   convenience struct device pointer for decoder device
> >>   * @dev_enc:   convenience struct device pointer for encoder device
> >> + * @fw:                a struct for venus firmware info
> >>   * @no_tz:     a flag that suggests presence of trustzone
> >>   * @lock:      a lock for this strucure
> >>   * @instances: a list_head of all instances
> >> @@ -130,6 +136,7 @@ struct venus_core {
> >>         struct device *dev;
> >>         struct device *dev_dec;
> >>         struct device *dev_enc;
> >> +       struct video_firmware fw;
> >
> > Since struct video_firmware is only used here I think you can declare
> > it inline, i.e.
> >
> >     struct {
> >         struct device *dev;
> >         struct iommu_domain *iommu_domain;
> >     } fw;
> >
> > This structure is actually a good candidate to hold the firmware
> > memory area start address and size.
>
> I can make it inline.
> Memory area and size are common parameters populated
> locally while loading the firmware with or without tz. Firmware struct
> has
> info more specific to firmware device.
>
> [snip]
>
> >
> >> +{
> >> +       struct iommu_domain *iommu_dom;
> >> +       struct device *dev;
> >> +       int ret;
> >> +
> >> +       dev = core->fw.dev;
> >> +       if (!dev)
> >> +               return -EPROBE_DEFER;
> >> +
> >> +       iommu_dom = iommu_domain_alloc(&platform_bus_type);
> >> +       if (!iommu_dom) {
> >> +               dev_err(dev, "Failed to allocate iommu domain\n");
> >> +               return -ENOMEM;
> >> +       }
> >> +
> >> +       ret = iommu_attach_device(iommu_dom, dev);
> >> +       if (ret) {
> >> +               dev_err(dev, "could not attach device\n");
> >> +               goto err_attach;
> >> +       }
> >
> > I think like the above belongs more in venus_firmware_init()
> > (introduced in patch 4/4) than here. There is no reason to
> > detach/reattach the iommu if we stop the firmware.
>
> Consider the case when we want to reload the firmware during error
> recovery.
> Boot and shutdown will be needed in such case without the need to
> populate
> the firmware device again.

Is there a need to reattach the iommu domain in case of an error?