linux-kernel - Re: [PATCH v7 4/5] media: platform: mediatek: isp: add mediatek ISP3.0 camsv

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Message-ID: <CAEHHSvbScBhn=6rSOApQ=K9JEpwL6JPpJnJy929mLXHhxQ=3FQ@mail.gmail.com>
Date: Mon, 25 Nov 2024 15:40:18 +0100
From: Julien Stephan <jstephan@...libre.com>
To: CK Hu (胡俊光) <ck.hu@...iatek.com>
Cc: "mchehab@...nel.org" <mchehab@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>, 
	"robh@...nel.org" <robh@...nel.org>, Andy Hsieh (謝智皓) <Andy.Hsieh@...iatek.com>, 
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>, 
	"laurent.pinchart@...asonboard.com" <laurent.pinchart@...asonboard.com>, 
	"krzk+dt@...nel.org" <krzk+dt@...nel.org>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>, 
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>, 
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"paul.elder@...asonboard.com" <paul.elder@...asonboard.com>, 
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, 
	"fsylvestre@...libre.com" <fsylvestre@...libre.com>, "pnguyen@...libre.com" <pnguyen@...libre.com>
Subject: Re: [PATCH v7 4/5] media: platform: mediatek: isp: add mediatek
 ISP3.0 camsv

Le lun. 25 nov. 2024 à 09:14, CK Hu (胡俊光) <ck.hu@...iatek.com> a écrit :
>
> Hi, Julien:
>
> On Thu, 2024-11-21 at 09:53 +0100, Julien Stephan wrote:
> > External email : Please do not click links or open attachments until you have verified the sender or the content.
> >
> >
> > From: Phi-bang Nguyen <pnguyen@...libre.com>
> >
> > This driver provides a path to bypass the SoC ISP so that image data
> > coming from the SENINF can go directly into memory without any image
> > processing. This allows the use of an external ISP.
> >
> > Signed-off-by: Phi-bang Nguyen <pnguyen@...libre.com>
> > Signed-off-by: Florian Sylvestre <fsylvestre@...libre.com>
> > [Paul Elder fix irq locking]
> > Signed-off-by: Paul Elder <paul.elder@...asonboard.com>
> > Co-developed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > Co-developed-by: Julien Stephan <jstephan@...libre.com>
> > Signed-off-by: Julien Stephan <jstephan@...libre.com>
> > ---
>
> [snip]
>
> > +static void mtk_camsv30_update_buffers_add(struct mtk_cam_dev *cam_dev,
> > +                                          struct mtk_cam_dev_buffer *buf)
> > +{
> > +       mtk_camsv30_img0_write(cam_dev, CAMSV_IMGO_SV_BASE_ADDR, buf->daddr);
> > +}
> > +
>
> [snip]
>
> > +static void mtk_camsv30_fbc_inc(struct mtk_cam_dev *cam_dev)
> > +{
> > +       unsigned int fbc_val;
> > +
> > +       if (pm_runtime_resume_and_get(cam_dev->dev) < 0) {
>
> I think this pm_runtime_resume_and_get() is not necessary.
> mtk_camsv30_fbc_inc() is called only in mtk_cam_vb2_buf_queue().
> But when buf_list is empty, mtk_camsv30_update_buffers_add() is called before this function.
> But mtk_camsv30_update_buffers_add() does not call pm_runtime_resume_and_get() and it works normally.
> So this function is not necessary to call pm_runtime_resume_and_get().

Hi CK,

This one is actually needed because .buf_queue can be called before
.start_streaming in case a user requests to prepare buffers before
streaming.
But you are right, if a user requests to alloc buffer before streaming
mtk_camsv_update_buffers_address will be called without pm. Streaming
still works because in start streaming we call
mtk_camsv_update_buffers_address again.
So maybe I should put the pm stuff in mtk_cam_vb2_buf_queue ?

Cheers
Julien


>
> In other register setting function, please also check this pm function is necessary or not.
>
> Regards,
> CK
>
> > +               dev_err(cam_dev->dev, "failed to get pm_runtime\n");
> > +               return;
> > +       }
> > +
> > +       fbc_val = mtk_camsv30_read(cam_dev, CAMSV_IMGO_FBC);
> > +       fbc_val |= CAMSV_IMGO_FBC_RCNT_INC;
> > +       mtk_camsv30_write(cam_dev, CAMSV_IMGO_FBC, fbc_val);
> > +       fbc_val &= ~CAMSV_IMGO_FBC_RCNT_INC;
> > +       mtk_camsv30_write(cam_dev, CAMSV_IMGO_FBC, fbc_val);
> > +
> > +       pm_runtime_put_autosuspend(cam_dev->dev);
> > +}
> > +
>
> >
>
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