Message-ID: <11b573d5-ce4d-476c-b94c-216d427cd838@linaro.org>
Date: Mon, 14 Jul 2025 17:16:46 +0300
From: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
 Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: Bryan O'Donoghue <bod@...nel.org>, linux-arm-msm@...r.kernel.org,
 linux-phy@...ts.infradead.org, linux-media@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] phy: qcom-mipi-csi2: Add a CSI2 MIPI D-PHY driver

On 7/10/25 19:16, Bryan O'Donoghue wrote:
> Add a new MIPI CSI2 driver in D-PHY mode initially. The entire set of
> existing CAMSS CSI PHY init sequences are imported in order to save time
> and effort in later patches.
> 
> In-line with other PHY drivers the process node name is omitted from the
> compat string while the soc name is included.
> 
> At the moment we follow the assignment of lane positions - the bitmap of
> physical input lanes to logical lane numbers as a linear list per the
> existing DPHY @lanes data-member.
> 
> This is fine for us in upstream since we also map the lanes contiguously
> but, our hardware can support different lane mappings so we should in the
> future extend out the DPHY structure to capture the mapping.
> 
> The Qualcomm 3PH class of PHYs can do both D-PHY and C-PHY mode. For now only
> D-PHY is supported.
> 
> In porting some of the logic over from camss-csiphy*.c to here its also
> possible to rationalise some of the code.
> 
> In particular use of regulator_bulk and clk_bulk as well as dropping the
> seemingly useless and unused interrupt handler.
> 
> The PHY sequences and a lot of the logic that goes with them are well proven
> in CAMSS and mature so the main thing to watch out for here is how to get
> the right sequencing of regulators, clocks and register-writes.
> 
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
> ---
>   MAINTAINERS                                        |  11 +
>   drivers/phy/qualcomm/Kconfig                       |  11 +
>   drivers/phy/qualcomm/Makefile                      |   6 +
>   drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c | 491 +++++++++++++++++++++
>   drivers/phy/qualcomm/phy-qcom-mipi-csi2-core.c     | 281 ++++++++++++
>   drivers/phy/qualcomm/phy-qcom-mipi-csi2.h          | 101 +++++
>   6 files changed, 901 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1ef99240a57ed1ad0d4501998970c7c3b85d3b81..69519e2d6dfb65771a3245735283645bb50a249a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20536,6 +20536,17 @@ S:	Maintained
>   F:	Documentation/devicetree/bindings/media/qcom,*-iris.yaml
>   F:	drivers/media/platform/qcom/iris/
>   
> +QUALCOMM MIPI CSI2 PHY DRIVER
> +M:	Bryan O'Donoghue <bod@...nel.org>
> +L:	linux-phy@...ts.infradead.org
> +L:	linux-media@...r.kernel.org
> +L:	linux-arm-msm@...r.kernel.org
> +S:	Supported
> +F:	Documentation/devicetree/bindings/phy/qcom,x1e80100-mipi-csi2-combo-phy.yaml
> +F:	drivers/phy/qualcomm/phy-qcom-mipi-csi2*.c
> +F:	drivers/phy/qualcomm/phy-qcom-mipi-csi2*.h
> +F:	include/dt-bindings/phy/phy-qcom-mipi-csi2*
> +
>   QUALCOMM NAND CONTROLLER DRIVER
>   M:	Manivannan Sadhasivam <mani@...nel.org>
>   L:	linux-mtd@...ts.infradead.org
> diff --git a/drivers/phy/qualcomm/Kconfig b/drivers/phy/qualcomm/Kconfig
> index ef14f4e33973cff4103d8ea3b07cfd62d344e450..d0ab70827519c2b046d0fb03c14bb4d8ae2ec9a1 100644
> --- a/drivers/phy/qualcomm/Kconfig
> +++ b/drivers/phy/qualcomm/Kconfig
> @@ -28,6 +28,17 @@ config PHY_QCOM_EDP
>   	  Enable this driver to support the Qualcomm eDP PHY found in various
>   	  Qualcomm chipsets.
>   
> +config PHY_QCOM_MIPI_CSI2
> +	tristate "Qualcomm MIPI CSI2 PHY driver"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	depends on OF
> +	depends on COMMON_CLK
> +	select GENERIC_PHY
> +	select GENERIC_PHY_MIPI_DPHY
> +	help
> +	  Enable this to support the MIPI CSI2 PHY driver found in various
> +	  Qualcomm chipsets.
> +
>   config PHY_QCOM_IPQ4019_USB
>   	tristate "Qualcomm IPQ4019 USB PHY driver"
>   	depends on OF && (ARCH_QCOM || COMPILE_TEST)
> diff --git a/drivers/phy/qualcomm/Makefile b/drivers/phy/qualcomm/Makefile
> index 3851e28a212d4a677a5b41805868f38b9ab49841..67013d27cb0387b9d65dcbe030ea6e5eaaabbe91 100644
> --- a/drivers/phy/qualcomm/Makefile
> +++ b/drivers/phy/qualcomm/Makefile
> @@ -5,6 +5,12 @@ obj-$(CONFIG_PHY_QCOM_EDP)		+= phy-qcom-edp.o
>   obj-$(CONFIG_PHY_QCOM_IPQ4019_USB)	+= phy-qcom-ipq4019-usb.o
>   obj-$(CONFIG_PHY_QCOM_IPQ806X_SATA)	+= phy-qcom-ipq806x-sata.o
>   obj-$(CONFIG_PHY_QCOM_M31_USB)		+= phy-qcom-m31.o
> +
> +phy-qcom-mipi-csi2-objs			+= phy-qcom-mipi-csi2-core.o \
> +					   phy-qcom-mipi-csi2-3ph-dphy.o
> +
> +obj-$(CONFIG_PHY_QCOM_MIPI_CSI2)	+= phy-qcom-mipi-csi2.o
> +
>   obj-$(CONFIG_PHY_QCOM_PCIE2)		+= phy-qcom-pcie2.o
>   
>   obj-$(CONFIG_PHY_QCOM_QMP_COMBO)	+= phy-qcom-qmp-combo.o phy-qcom-qmp-usbc.o
> diff --git a/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c b/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..1a99efee88cc94ec0d29a335cd29f88af8a00c02
> --- /dev/null
> +++ b/drivers/phy/qualcomm/phy-qcom-mipi-csi2-3ph-dphy.c
> @@ -0,0 +1,491 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * camss-phy_qcom_mipi_csi2-3ph-1-0.c
> + *
> + * Qualcomm MSM Camera Subsystem - CSIPHY Module 3phase v1.0
> + *
> + * Copyright (c) 2011-2015, The Linux Foundation. All rights reserved.
> + * Copyright (C) 2016-2025 Linaro Ltd.
> + */
> +#define DEBUG

Still under debugging?..

Well, the phy should be a multimedia device, and this driver is not
the one, thus you can not use it to connect sensors and put the IP
into a media pipeline.

-- 
Best wishes,
Vladimir

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