On Wed, Sep 05, 2018 at 04:46:05PM +0300, Laurent Pinchart wrote:

Hi Maxime,

Thank you for the patch.

On Wednesday, 5 September 2018 12:16:35 EEST Maxime Ripard wrote:

quoted

The MIPI D-PHY spec defines default values and boundaries for most of the
parameters it defines. Introduce helpers to help drivers get meaningful
values based on their current parameters, and validate the boundaries of
these parameters if needed.

Signed-off-by: Maxime Ripard <redacted>
---
 drivers/phy/Kconfig               |   8 ++-
 drivers/phy/Makefile              |   1 +-
 drivers/phy/phy-core-mipi-dphy.c  | 160 +++++++++++++++++++++++++++++++-
 include/linux/phy/phy-mipi-dphy.h |   6 +-
 4 files changed, 175 insertions(+)
 create mode 100644 drivers/phy/phy-core-mipi-dphy.c

diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
index 5c8d452e35e2..06bd22bd1f4a 100644
--- a/drivers/phy/Kconfig
+++ b/drivers/phy/Kconfig

@@ -15,6 +15,14 @@ config GENERIC_PHY
 	  phy users can obtain reference to the PHY. All the users of this
 	  framework should select this config.

+config GENERIC_PHY_MIPI_DPHY
+	bool "MIPI D-PHY support"
+	help
+	  Generic MIPI D-PHY support.
+
+	  Provides a number of helpers a core functions for MIPI D-PHY
+	  drivers to us.

Do we really need to make this user-selectable ?

Probably not :)

quoted

 config PHY_LPC18XX_USB_OTG
 	tristate "NXP LPC18xx/43xx SoC USB OTG PHY driver"
 	depends on OF && (ARCH_LPC18XX || COMPILE_TEST)

diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
index 84e3bd9c5665..71c29d2b9af7 100644
--- a/drivers/phy/Makefile
+++ b/drivers/phy/Makefile

@@ -4,6 +4,7 @@
 #

 obj-$(CONFIG_GENERIC_PHY)		+= phy-core.o
+obj-$(CONFIG_GENERIC_PHY_MIPI_DPHY)	+= phy-core-mipi-dphy.o
 obj-$(CONFIG_PHY_LPC18XX_USB_OTG)	+= phy-lpc18xx-usb-otg.o
 obj-$(CONFIG_PHY_XGENE)			+= phy-xgene.o
 obj-$(CONFIG_PHY_PISTACHIO_USB)		+= phy-pistachio-usb.o

diff --git a/drivers/phy/phy-core-mipi-dphy.c

b/drivers/phy/phy-core-mipi-dphy.c new file mode 100644
index 000000000000..6c1ddc7734a2

--- /dev/null
+++ b/drivers/phy/phy-core-mipi-dphy.c

@@ -0,0 +1,160 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2013 NVIDIA Corporation
+ * Copyright (C) 2018 Cadence Design Systems Inc.
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/time64.h>
+
+#include <linux/phy/phy.h>
+#include <linux/phy/phy-mipi-dphy.h>
+
+/*
+ * Default D-PHY timings based on MIPI D-PHY specification. Derived from

the
+ * valid ranges specified in Section 6.9, Table 14, Page 40 of the D-PHY
+ * specification (v1.2) with minor adjustments.

Could you list those adjustments ?

I will. This was taken from the Tegra DSI driver, so I'm not sure what
these are exactly, but that should be addressed.

quoted

+ */
+int phy_mipi_dphy_get_default_config(unsigned long pixel_clock,
+				     unsigned int bpp,
+				     unsigned int lanes,
+				     struct phy_configure_opts_mipi_dphy *cfg)
+{
+	unsigned long hs_clk_rate;
+	unsigned long ui;
+
+	if (!cfg)
+		return -EINVAL;

Should we really expect cfg to be NULL ?

It avoids a kernel panic and it's not in a hot patch, so I'd say yes?

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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