Re: [PATCH v10 07/17] media: mali-c55: Add Mali-C55 ISP driver

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Laurent,

On Sun, Jun 29, 2025 at 09:35:47PM +0300, Laurent Pinchart wrote:
> On Sat, Jun 28, 2025 at 11:06:54PM +0300, Sakari Ailus wrote:
> > On 6/24/25 13:21, Daniel Scally wrote:
> 
> [snip]
> 
> > > diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-isp.c b/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> > > new file mode 100644
> > > index 0000000000000000000000000000000000000000..20d4d16c75fbf0d5519ecadb5ed1d080bdae05de
> > > --- /dev/null
> > > +++ b/drivers/media/platform/arm/mali-c55/mali-c55-isp.c
> > > @@ -0,0 +1,656 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * ARM Mali-C55 ISP Driver - Image signal processor
> > > + *
> > > + * Copyright (C) 2024 Ideas on Board Oy
> > 
> > It's 2025 already.
> > 
> > > + */
> > > +
> > > +#include <linux/delay.h>
> > > +#include <linux/iopoll.h>
> > > +#include <linux/property.h>
> > > +#include <linux/string.h>
> > > +
> > > +#include <linux/media/arm/mali-c55-config.h>
> > 
> > If this is a UAPI header, please include uapi in the path, too.
> > 
> > Earlier such headers have been under include/uapi/linux, I don't object 
> > putting new ones elsewhere in principle though. Just check with Hans and 
> > Laurent, too... I don't have an opinion yet really.
> 
> With each new media header we add to include/uapi/linux/, I wish
> stronger and stronger that we had created include/uapi/linux/media/. We
> don't have to do it now, my regret will just grow stronger :-)

I'm fine with using include/uapi/linux/media/.

> 
> > > +/* NOT const because the default needs to be filled in at runtime */
> > > +static struct v4l2_ctrl_config mali_c55_isp_v4l2_custom_ctrls[] = {
> > > +	{
> > > +		.ops = &mali_c55_isp_ctrl_ops,
> > > +		.id = V4L2_CID_MALI_C55_CAPABILITIES,
> > > +		.name = "Mali-C55 ISP Capabilities",
> > > +		.type = V4L2_CTRL_TYPE_BITMASK,
> > > +		.min = 0,
> > > +		.max = MALI_C55_GPS_PONG_FITTED |
> > > +		       MALI_C55_GPS_WDR_FITTED |
> > > +		       MALI_C55_GPS_COMPRESSION_FITTED |
> > > +		       MALI_C55_GPS_TEMPER_FITTED |
> > > +		       MALI_C55_GPS_SINTER_LITE_FITTED |
> > > +		       MALI_C55_GPS_SINTER_FITTED |
> > > +		       MALI_C55_GPS_IRIDIX_LTM_FITTED |
> > > +		       MALI_C55_GPS_IRIDIX_GTM_FITTED |
> > > +		       MALI_C55_GPS_CNR_FITTED |
> > > +		       MALI_C55_GPS_FRSCALER_FITTED |
> > > +		       MALI_C55_GPS_DS_PIPE_FITTED,
> > > +		.def = 0,
> > > +	},
> > > +};
> > > +
> > > +static int mali_c55_isp_init_controls(struct mali_c55 *mali_c55)
> > > +{
> > > +	struct v4l2_ctrl_handler *handler = &mali_c55->isp.handler;
> > > +	struct v4l2_ctrl *capabilities;
> > > +	int ret;
> > > +
> > > +	ret = v4l2_ctrl_handler_init(handler, 1);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	mali_c55_isp_v4l2_custom_ctrls[0].def = mali_c55->capabilities;
> > 
> > The capabilities here are still specific to a device, not global, in 
> > principle at least. Can you move it here, as a local variable?
> > 
> > > +
> > > +	capabilities = v4l2_ctrl_new_custom(handler,
> > > +					    &mali_c55_isp_v4l2_custom_ctrls[0],
> > > +					    NULL);
> > > +	if (capabilities)
> > > +		capabilities->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > > +
> > > +	if (handler->error) {
> > > +		dev_err(mali_c55->dev, "failed to register capabilities control\n");
> > > +		v4l2_ctrl_handler_free(handler);
> > > +		return handler->error;
> > 
> > v4l2_ctrl_handler_free() will return the error soon, presumably sooner 
> > than the above code makes it to upstream. Before that, this pattern 
> > won't work as v4l2_ctrl_handler_free() also resets the handler's error 
> > field. :-)
> > 
> > > diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-registers.h b/drivers/media/platform/arm/mali-c55/mali-c55-registers.h
> > > new file mode 100644
> > > index 0000000000000000000000000000000000000000..36a81be0191a15da91809dd2da5d279716f6d725
> > > --- /dev/null
> > > +++ b/drivers/media/platform/arm/mali-c55/mali-c55-registers.h
> > > @@ -0,0 +1,318 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +/*
> > > + * ARM Mali-C55 ISP Driver - Register definitions
> > > + *
> > > + * Copyright (C) 2024 Ideas on Board Oy
> > > + */
> > > +
> > > +#ifndef _MALI_C55_REGISTERS_H
> > > +#define _MALI_C55_REGISTERS_H
> > > +
> > > +#include <linux/bits.h>
> > > +
> > > +/* ISP Common 0x00000 - 0x000ff */
> > > +
> > > +#define MALI_C55_REG_API				0x00000
> > > +#define MALI_C55_REG_PRODUCT				0x00004
> > > +#define MALI_C55_REG_VERSION				0x00008
> > > +#define MALI_C55_REG_REVISION				0x0000c
> > > +#define MALI_C55_REG_PULSE_MODE				0x0003c
> > > +#define MALI_C55_REG_INPUT_MODE_REQUEST			0x0009c
> > > +#define MALI_C55_INPUT_SAFE_STOP			0x00
> > > +#define MALI_C55_INPUT_SAFE_START			0x01
> > > +#define MALI_C55_REG_MODE_STATUS			0x000a0
> > > +#define MALI_C55_REG_INTERRUPT_MASK_VECTOR		0x00030
> > > +#define MALI_C55_INTERRUPT_MASK_ALL			GENMASK(31, 0)
> > > +
> > > +#define MALI_C55_REG_GLOBAL_MONITOR			0x00050
> > > +
> > > +#define MALI_C55_REG_GEN_VIDEO				0x00080
> > > +#define MALI_C55_REG_GEN_VIDEO_ON_MASK			BIT(0)
> > > +#define MALI_C55_REG_GEN_VIDEO_MULTI_MASK		BIT(1)
> > > +#define MALI_C55_REG_GEN_PREFETCH_MASK			GENMASK(31, 16)
> > > +
> > > +#define MALI_C55_REG_MCU_CONFIG				0x00020
> > > +#define MALI_C55_REG_MCU_CONFIG_OVERRIDE_MASK		BIT(0)
> > > +#define MALI_C55_REG_MCU_CONFIG_WRITE_MASK		BIT(1)
> > > +#define MALI_C55_MCU_CONFIG_WRITE(x)			((x) << 1)
> > 
> > Is x unsigned?
> 
> Does it matter ? The reason why the BIT() macro uses (UL(1) << (nr))
> instead of (1 << (nr)) is (if I'm not mistaken) to avoid incorrect
> handling of bit 31. As long as x doesn't take negative values and
> doesn't extend to bit 31, it should be fine.

For that reason exactly. If you're unsure, maybe at least cast it as
unsigned?

> 
> > > +#define MALI_C55_REG_MCU_CONFIG_WRITE_PING		BIT(1)
> > > +#define MALI_C55_REG_MCU_CONFIG_WRITE_PONG		0x00
> > > +#define MALI_C55_REG_MULTI_CONTEXT_MODE_MASK		BIT(8)
> > > +#define MALI_C55_REG_PING_PONG_READ			0x00024
> > > +#define MALI_C55_REG_PING_PONG_READ_MASK		BIT(2)
> > > +#define MALI_C55_INTERRUPT_BIT(x)			BIT(x)
> > > +
> > > +#define MALI_C55_REG_GLOBAL_PARAMETER_STATUS		0x00068
> > > +#define MALI_C55_GPS_PONG_FITTED			BIT(0)
> > > +#define MALI_C55_GPS_WDR_FITTED				BIT(1)
> > > +#define MALI_C55_GPS_COMPRESSION_FITTED			BIT(2)
> > > +#define MALI_C55_GPS_TEMPER_FITTED			BIT(3)
> > > +#define MALI_C55_GPS_SINTER_LITE_FITTED			BIT(4)
> > > +#define MALI_C55_GPS_SINTER_FITTED			BIT(5)
> > > +#define MALI_C55_GPS_IRIDIX_LTM_FITTED			BIT(6)
> > > +#define MALI_C55_GPS_IRIDIX_GTM_FITTED			BIT(7)
> > > +#define MALI_C55_GPS_CNR_FITTED				BIT(8)
> > > +#define MALI_C55_GPS_FRSCALER_FITTED			BIT(9)
> > > +#define MALI_C55_GPS_DS_PIPE_FITTED			BIT(10)
> > > +
> > > +#define MALI_C55_REG_BLANKING				0x00084
> > > +#define MALI_C55_REG_HBLANK_MASK			GENMASK(15, 0)
> > > +#define MALI_C55_REG_VBLANK_MASK			GENMASK(31, 16)
> > > +#define MALI_C55_VBLANK(x)				((x) << 16)
> > 
> > Same question for the bit shifts left elsewhere in the header.
> > 
> > > +
> > > +#define MALI_C55_REG_HC_START				0x00088
> > > +#define MALI_C55_HC_START(h)				(((h) & 0xffff) << 16)
> > > +#define MALI_C55_REG_HC_SIZE				0x0008c
> > > +#define MALI_C55_HC_SIZE(h)				((h) & 0xffff)
> > > +#define MALI_C55_REG_VC_START_SIZE			0x00094
> > > +#define MALI_C55_VC_START(v)				((v) & 0xffff)
> > > +#define MALI_C55_VC_SIZE(v)				(((v) & 0xffff) << 16)
> > > +
> > > +/* Ping/Pong Configuration Space */
> > > +#define MALI_C55_REG_BASE_ADDR				0x18e88
> > > +#define MALI_C55_REG_BYPASS_0				0x18eac
> > > +#define MALI_C55_REG_BYPASS_0_VIDEO_TEST		BIT(0)
> > > +#define MALI_C55_REG_BYPASS_0_INPUT_FMT			BIT(1)
> > > +#define MALI_C55_REG_BYPASS_0_DECOMPANDER		BIT(2)
> > > +#define MALI_C55_REG_BYPASS_0_SENSOR_OFFSET_WDR		BIT(3)
> > > +#define MALI_C55_REG_BYPASS_0_GAIN_WDR			BIT(4)
> > > +#define MALI_C55_REG_BYPASS_0_FRAME_STITCH		BIT(5)
> > > +#define MALI_C55_REG_BYPASS_1				0x18eb0
> > > +#define MALI_C55_REG_BYPASS_1_DIGI_GAIN			BIT(0)
> > > +#define MALI_C55_REG_BYPASS_1_FE_SENSOR_OFFS		BIT(1)
> > > +#define MALI_C55_REG_BYPASS_1_FE_SQRT			BIT(2)
> > > +#define MALI_C55_REG_BYPASS_1_RAW_FE			BIT(3)
> > > +#define MALI_C55_REG_BYPASS_2				0x18eb8
> > > +#define MALI_C55_REG_BYPASS_2_SINTER			BIT(0)
> > > +#define MALI_C55_REG_BYPASS_2_TEMPER			BIT(1)
> > > +#define MALI_C55_REG_BYPASS_3				0x18ebc
> > > +#define MALI_C55_REG_BYPASS_3_SQUARE_BE			BIT(0)
> > > +#define MALI_C55_REG_BYPASS_3_SENSOR_OFFSET_PRE_SH	BIT(1)
> > > +#define MALI_C55_REG_BYPASS_3_MESH_SHADING		BIT(3)
> > > +#define MALI_C55_REG_BYPASS_3_WHITE_BALANCE		BIT(4)
> > > +#define MALI_C55_REG_BYPASS_3_IRIDIX			BIT(5)
> > > +#define MALI_C55_REG_BYPASS_3_IRIDIX_GAIN		BIT(6)
> > > +#define MALI_C55_REG_BYPASS_4				0x18ec0
> > > +#define MALI_C55_REG_BYPASS_4_DEMOSAIC_RGB		BIT(1)
> > > +#define MALI_C55_REG_BYPASS_4_PF_CORRECTION		BIT(3)
> > > +#define MALI_C55_REG_BYPASS_4_CCM			BIT(4)
> > > +#define MALI_C55_REG_BYPASS_4_CNR			BIT(5)
> > > +#define MALI_C55_REG_FR_BYPASS				0x18ec4
> > > +#define MALI_C55_REG_DS_BYPASS				0x18ec8
> > > +#define MALI_C55_BYPASS_CROP				BIT(0)
> > > +#define MALI_C55_BYPASS_SCALER				BIT(1)
> > > +#define MALI_C55_BYPASS_GAMMA_RGB			BIT(2)
> > > +#define MALI_C55_BYPASS_SHARPEN				BIT(3)
> > > +#define MALI_C55_BYPASS_CS_CONV				BIT(4)
> > > +#define MALI_C55_REG_ISP_RAW_BYPASS			0x18ecc
> > > +#define MALI_C55_ISP_RAW_BYPASS_BYPASS_MASK		BIT(0)
> > > +#define MALI_C55_ISP_RAW_BYPASS_FR_BYPASS_MASK		GENMASK(9, 8)
> > > +#define MALI_C55_ISP_RAW_BYPASS_RAW_FR_BYPASS		(2 << 8)
> > > +#define MALI_C55_ISP_RAW_BYPASS_RGB_FR_BYPASS		(1 << 8)
> > 
> > BIT() or make these unsigned.
> 
> It's a 2 bits field, BIT() isn't appropriate.

That leaves us with the other alternative, doesn't it?

-- 
Kind regards,

Sakari Ailus