From: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
To: "Jernej Škrabec" <jernej.skrabec@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-sunxi@lists.linux.dev, Yong Deng <yong.deng@magewell.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Chen-Yu Tsai <wens@csie.org>,
Samuel Holland <samuel@sholland.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH v3 03/46] media: sun6i-csi: Grab bus clock instead of passing it to regmap
Date: Fri, 18 Mar 2022 09:49:04 +0100 [thread overview]
Message-ID: <YjRHgGgYfYODAmoi@aptenodytes> (raw)
In-Reply-To: <2361247.jE0xQCEvom@kista>
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Hi Jernej,
On Tue 15 Mar 22, 20:22, Jernej Škrabec wrote:
> Hi Paul!
>
> Dne petek, 11. marec 2022 ob 15:34:49 CET je Paul Kocialkowski napisal(a):
> > Since the bus clock alone is not enough to get access to the registers,
> > don't pass it to regmap and manage it instead just like the other
> > clocks.
> >
>
> Let me ask it in another way, is bus clock needed only for register access? If
> yes, it makes sense to keep it enabled only during register access.
Ah right, I lost sight that what regmap will do is to enable/disable the
clock around register access. I understand there might be an advantage
in terms of power consumption here.
I haven't checked specifically, but since it was used like that before
it's probably fine.
Out of curiosity: is there any noticeable latency added by the process?
Cheers,
Paul
> Best regards,
> Jernej
>
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> > ---
> > drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c | 10 ++++++++--
> > drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h | 1 +
> > 2 files changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/
> media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > index 5fbaa1e99412..dc79f3c14336 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > @@ -827,13 +827,19 @@ static int sun6i_csi_resource_request(struct
> sun6i_csi_device *csi_dev,
> > if (IS_ERR(io_base))
> > return PTR_ERR(io_base);
> >
> > - csi_dev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "bus",
> io_base,
> > -
> &sun6i_csi_regmap_config);
> > + csi_dev->regmap = devm_regmap_init_mmio(&pdev->dev, io_base,
> > +
> &sun6i_csi_regmap_config);
> > if (IS_ERR(csi_dev->regmap)) {
> > dev_err(&pdev->dev, "Failed to init register map\n");
> > return PTR_ERR(csi_dev->regmap);
> > }
> >
> > + csi_dev->clk_bus = devm_clk_get(&pdev->dev, "bus");
> > + if (IS_ERR(csi_dev->clk_bus)) {
> > + dev_err(&pdev->dev, "Unable to acquire bus clock\n");
> > + return PTR_ERR(csi_dev->clk_bus);
> > + }
> > +
> > csi_dev->clk_mod = devm_clk_get(&pdev->dev, "mod");
> > if (IS_ERR(csi_dev->clk_mod)) {
> > dev_err(&pdev->dev, "Unable to acquire csi clock\n");
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h b/drivers/
> media/platform/sunxi/sun6i-csi/sun6i_csi.h
> > index e4e7ac6c869f..356661b413f8 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.h
> > @@ -51,6 +51,7 @@ struct sun6i_csi_device {
> > struct sun6i_video video;
> >
> > struct regmap *regmap;
> > + struct clk *clk_bus;
> > struct clk *clk_mod;
> > struct clk *clk_ram;
> > struct reset_control *reset;
> > --
> > 2.35.1
> >
> >
>
>
--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2022-03-18 8:50 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 14:34 [PATCH v3 00/46] Allwinner A31/A83T MIPI CSI-2 and A31 ISP / CSI Rework Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 01/46] media: sun6i-csi: Define and use driver name and (reworked) description Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 02/46] media: sun6i-csi: Refactor main driver data structures Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 03/46] media: sun6i-csi: Grab bus clock instead of passing it to regmap Paul Kocialkowski
2022-03-15 19:22 ` Jernej Škrabec
2022-03-18 8:49 ` Paul Kocialkowski [this message]
2022-03-11 14:34 ` [PATCH v3 04/46] media: sun6i-csi: Tidy up platform code Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 05/46] media: sun6i-csi: Always set exclusive module clock rate Paul Kocialkowski
2022-03-15 19:27 ` Jernej Škrabec
2022-03-11 14:34 ` [PATCH v3 06/46] media: sun6i-csi: Define and use variant to get " Paul Kocialkowski
2022-03-15 19:31 ` Jernej Škrabec
2022-03-18 8:54 ` Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 07/46] media: sun6i-csi: Use runtime pm for clocks and reset Paul Kocialkowski
2022-03-15 19:46 ` Jernej Škrabec
2022-03-18 16:15 ` Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 08/46] media: sun6i-csi: Tidy up Kconfig Paul Kocialkowski
2022-03-15 19:51 ` Jernej Škrabec
2022-03-11 14:34 ` [PATCH v3 09/46] media: sun6i-csi: Tidy up v4l2 code Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 10/46] media: sun6i-csi: Tidy up video code Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 11/46] media: sun6i-csi: Pass and store csi device directly in " Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 12/46] media: sun6i-csi: Register the media device after creation Paul Kocialkowski
2022-03-11 14:34 ` [PATCH v3 13/46] media: sun6i-csi: Add media ops with link notify callback Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 14/46] media: sun6i-csi: Introduce and use video helper functions Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 15/46] media: sun6i-csi: Move csi buffer definition to main header file Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 16/46] media: sun6i-csi: Add bridge v4l2 subdev with port management Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 17/46] media: sun6i-csi: Rename sun6i_video to sun6i_csi_capture Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 18/46] media: sun6i-csi: Add capture state using vsync for page flip Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 19/46] media: sun6i-csi: Rework register definitions, invert misleading fields Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 20/46] media: sun6i-csi: Add dimensions and format helpers to capture Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 21/46] media: sun6i-csi: Implement address configuration without indirection Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 22/46] media: sun6i-csi: Split stream sequences and irq code in capture Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 23/46] media: sun6i-csi: Move power management to runtime pm " Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 24/46] media: sun6i-csi: Move register configuration to capture Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 25/46] media: sun6i-csi: Rework capture format management with helper Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 26/46] media: sun6i-csi: Remove custom format helper and rework configure Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 27/46] media: sun6i-csi: Add bridge dimensions and format helpers Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 28/46] media: sun6i-csi: Get mbus code from bridge instead of storing it Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 29/46] media: sun6i-csi: Tidy capture configure code Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 30/46] media: sun6i-csi: Introduce bridge format structure, list and helper Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 31/46] media: sun6i-csi: Introduce capture " Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 32/46] media: sun6i-csi: Configure registers from format tables Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 33/46] media: sun6i-csi: Introduce format match structure, list and helper Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 34/46] media: sun6i-csi: Implement capture link validation with logic Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 35/46] media: sun6i-csi: Get bridge subdev directly in capture stream ops Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 36/46] media: sun6i-csi: Move hardware control to the bridge Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 37/46] media: sun6i-csi: Unset bridge source on capture streamon fail Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 38/46] media: sun6i-csi: Rename the capture video device to sun6i-csi-capture Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 39/46] media: sun6i-csi: Cleanup headers and includes, update copyright lines Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 40/46] media: sun6i-csi: Add support for MIPI CSI-2 to the bridge code Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 41/46] media: sun6i-csi: Only configure capture when streaming Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 42/46] media: sun6i-csi: Add extra checks to the interrupt routine Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 43/46] media: sun6i-csi: Request a shared interrupt Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 44/46] media: sun6i-csi: Detect the availability of the ISP Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 45/46] media: sun6i-csi: Add support for hooking to the isp devices Paul Kocialkowski
2022-03-11 14:35 ` [PATCH v3 46/46] MAINTAINERS: Add myself as sun6i-csi maintainer and rename/move entry Paul Kocialkowski
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