Re: [RESEND RFC/PATCH 6/8] media: platform: mtk-vcodec: Add Mediatek V4L2 Video Encoder Driver

tiffany lin
2015-11-30T11:40:05Z

On Fri, 2015-11-27 at 16:34 +0000, Daniel Thompson wrote:
> Hi Tiffany/Andrew
>
> This review is a rather more superficial than my previous one. Mostly
> I'm just commenting on some of the bits I spotted whilst trying to find
> my way around the patchset.
>
> I hope to another more detailed review for v2 (and feel free to add me
> to Cc:).
>
Thanks for your comments.

>
> On 17/11/15 12:54, Tiffany Lin wrote:
> > Signed-off-by: Tiffany Lin <tiffany.lin@mediatek.com>
> > Signed-off-by: Andrew-CT Chen <andrew-ct.chen@mediatek.com>
>
> There is no description of what this patch does. Its not enough to have
> it on the cover letter (because that won't end up in version control).
> You need something here.
>
Got it, We will add description for each patch in next version.

>
> > diff --git a/drivers/media/platform/mtk-vcodec/Kconfig b/drivers/media/platform/mtk-vcodec/Kconfig
> > new file mode 100644
> > index 0000000..1c0b935
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/Kconfig
> > @@ -0,0 +1,5 @@
> > +config MEDIATEK_VPU
> > + bool
> > + ---help---
> > + This driver provides downloading firmware vpu (video processor unit)
> > + and communicating with vpu.
>
> Haven't I seen this before (in patch 3)? Why is it being added to
> another Kconfig file?
>
We will remove this in next version.

>
> > diff --git a/drivers/media/platform/mtk-vcodec/Makefile b/drivers/media/platform/mtk-vcodec/Makefile
> > new file mode 100644
> > index 0000000..c7f7174
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/Makefile
> > @@ -0,0 +1,12 @@
> > +obj-$(CONFIG_VIDEO_MEDIATEK_VCODEC) += mtk_vcodec_intr.o \
> > + mtk_vcodec_util.o \
> > + mtk_vcodec_enc_drv.o \
> > + mtk_vcodec_enc.o \
> > + mtk_vcodec_enc_pm.o
> > +
> > +obj-$(CONFIG_VIDEO_MEDIATEK_VCODEC) += common/
> > +
> > +ccflags-y += -I$(srctree)/drivers/media/platform/mtk-vcodec/include \
> > + -I$(srctree)/drivers/media/platform/mtk-vcodec \
> > + -I$(srctree)/drivers/media/platform/mtk-vpu
>
> Seems like there's a lot of directories here. Are these files
> (framework, common, vcodec, etc) so unrelated they really need to live
> in separate directories?
>
> Why not just drivers/media/platform/mediatek?
This is because VPU and Vcodec are two different drivers.
Driver in mtk-vpu is for controlling VPU device and provide
communication API to VPU.
Driver in mtk-vcodec is for control different encoder (vp8, h264), it
include v4l2 driver layer, glue layer between encoders and vp8 and h264
encoder.

>
>
> > diff --git a/drivers/media/platform/mtk-vcodec/common/Makefile b/drivers/media/platform/mtk-vcodec/common/Makefile
> > new file mode 100644
> > index 0000000..477ab80
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/common/Makefile
> > @@ -0,0 +1,8 @@
> > +obj-y += \
> > + venc_drv_if.o
> > +
> > +ccflags-y += \
> > + -I$(srctree)/include/ \
> > + -I$(srctree)/drivers/media/platform/mtk-vcodec \
> > + -I$(srctree)/drivers/media/platform/mtk-vcodec/include \
> > + -I$(srctree)/drivers/media/platform/mtk-vpu
>
> As above, this appears to be a directory to hold just one file.
>
Sorry, I didn't get it. Could you explain more?

>
> > diff --git a/drivers/media/platform/mtk-vcodec/common/venc_drv_if.c
> b/drivers/media/platform/mtk-vcodec/common/venc_drv_if.c
> > new file mode 100644
> > index 0000000..9b3f025
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/common/venc_drv_if.c
> > @@ -0,0 +1,152 @@
> > +/*
> > + * Copyright (c) 2015 MediaTek Inc.
> > + * Author: Daniel Hsiao <daniel.hsiao@mediatek.com>
> > + * Jungchang Tsao <jungchang.tsao@mediatek.com>
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/kernel.h>
> > +#include <linux/slab.h>
> > +
> > +#include "mtk_vcodec_drv.h"
> > +#include "mtk_vcodec_enc.h"
> > +#include "mtk_vcodec_pm.h"
> > +#include "mtk_vcodec_util.h"
> > +#include "mtk_vpu_core.h"
> > +
> > +#include "venc_drv_if.h"
> > +#include "venc_drv_base.h"
> > +
> > +
> > +int venc_if_create(void *ctx, unsigned int fourcc, unsigned long
> *handle)
> > +{
> > + struct venc_handle *h;
> > + char str[10];
> > +
> > + mtk_vcodec_fmt2str(fourcc, str);
> > +
> > + h = kzalloc(sizeof(*h), GFP_KERNEL);
> > + if (!h)
> > + return -ENOMEM;
> > +
> > + h->fourcc = fourcc;
> > + h->ctx = ctx;
> > + mtk_vcodec_debug(h, "fmt = %s handle = %p", str, h);
> > +
> > + switch (fourcc) {
> > + default:
> > + mtk_vcodec_err(h, "invalid format %s", str);
> > + goto err_out;
> > + }
> > +
> > + *handle = (unsigned long)h;
> > + return 0;
> > +
> > +err_out:
> > + kfree(h);
> > + return -EINVAL;
> > +}
> > +
> > +int venc_if_init(unsigned long handle)
> > +{
> > + int ret = 0;
> > + struct venc_handle *h = (struct venc_handle *)handle;
> > +
> > + mtk_vcodec_debug_enter(h);
> > +
> > + mtk_venc_lock(h->ctx);
> > + mtk_vcodec_enc_clock_on();
> > + vpu_enable_clock(vpu_get_plat_device(h->ctx->dev->plat_dev));
> > + ret = h->enc_if->init(h->ctx, (unsigned long *)&h->drv_handle);
> > + vpu_disable_clock(vpu_get_plat_device(h->ctx->dev->plat_dev));
> > + mtk_vcodec_enc_clock_off();
> > + mtk_venc_unlock(h->ctx);
> > +
> > + return ret;
> > +}
>
> To me this looks more like an obfuscation layer rather than a
> abstraction layer. I don't understand why we need to hide things from
> the V4L2 implementation that this code forms part of.
>
> More importantly, if this code was included somewhere where it could be
> properly integrated with the device model you might be able to use the
> pm_runtime system to avoid this sort of "heroics" to manage the clocks
> anyway.
>
We want to abstract common part from encoder driver.
Every encoder driver follow same calling flow and only need to take care
about how to communicate with vpu to encode specific format.
Encoder driver do not need to take care clock and multiple instance
issue.

>
> > diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h b/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h
> > new file mode 100644
> > index 0000000..22239f8
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h
> > @@ -0,0 +1,441 @@
> > +/*
> > +* Copyright (c) 2015 MediaTek Inc.
> > +* Author: PC Chen <pc.chen@mediatek.com>
> > +* Tiffany Lin <tiffany.lin@mediatek.com>
> > +*
> > +* This program is free software; you can redistribute it and/or modify
> > +* it under the terms of the GNU General Public License version 2 as
> > +* published by the Free Software Foundation.
> > +*
> > +* This program is distributed in the hope that it will be useful,
> > +* but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > +* GNU General Public License for more details.
> > +*/
> > +
> > +#ifndef _MTK_VCODEC_DRV_H_
> > +#define _MTK_VCODEC_DRV_H_
> > +
> > +#include <linux/platform_device.h>
> > +#include <linux/videodev2.h>
> > +#include <media/v4l2-ctrls.h>
> > +#include <media/v4l2-device.h>
> > +#include <media/v4l2-ioctl.h>
> > +#include <media/videobuf2-core.h>
> > +#include <media/videobuf2-v4l2.h>
> > +
> > +#include "venc_drv_if.h"
> > +
> > +#define MTK_VCODEC_MAX_INSTANCES 32
> > +#define MTK_VCODEC_MAX_FRAME_SIZE 0x800000
> > +#define MTK_VIDEO_MAX_FRAME 32
> > +#define MTK_MAX_CTRLS 10
> > +
> > +#define MTK_VCODEC_DRV_NAME "mtk_vcodec_drv"
> > +#define MTK_VCODEC_ENC_NAME "mtk-vcodec-enc"
> > +
> > +#define MTK_VENC_IRQ_STATUS_SPS 0x1
> > +#define MTK_VENC_IRQ_STATUS_PPS 0x2
> > +#define MTK_VENC_IRQ_STATUS_FRM 0x4
> > +#define MTK_VENC_IRQ_STATUS_DRAM 0x8
> > +#define MTK_VENC_IRQ_STATUS_PAUSE 0x10
> > +#define MTK_VENC_IRQ_STATUS_SWITCH 0x20
>
> Probably better to use BIT(0) .. BIT(5).
Will change to use BIT(0) in next version.

>
>
> > +#define MTK_VENC_IRQ_STATUS_OFFSET 0x05C
> > +#define MTK_VENC_IRQ_ACK_OFFSET 0x060
> > +
> > +#define MTK_VCODEC_MAX_PLANES 3
> > +
> > +#define VDEC_HW_ACTIVE 0x10
> > +#define VDEC_IRQ_CFG 0x11
> > +#define VDEC_IRQ_CLR 0x10
> > +
> > +#define VDEC_IRQ_CFG_REG 0xa4
> > +#define NUM_MAX_ALLOC_CTX 4
> > +#define MTK_V4L2_BENCHMARK 0
> > +#define USE_ENCODE_THREAD 1
> > +
> > +/**
> > + * enum mtk_hw_reg_idx - MTK hw register base index
> > + */
> > +enum mtk_hw_reg_idx {
> > + VDEC_SYS,
> > + VDEC_MISC,
> > + VDEC_LD,
> > + VDEC_TOP,
> > + VDEC_CM,
> > + VDEC_AD,
> > + VDEC_AV,
> > + VDEC_PP,
> > + VDEC_HWD,
> > + VDEC_HWQ,
> > + VDEC_HWB,
> > + VDEC_HWG,
> > + NUM_MAX_VDEC_REG_BASE,
> > + VENC_SYS = NUM_MAX_VDEC_REG_BASE,
> > + VENC_LT_SYS,
> > + NUM_MAX_VCODEC_REG_BASE
> > +};
> > +
> > +/**
> > + * enum mtk_instance_type - The type of an MTK Vcodec instance.
> > + */
> > +enum mtk_instance_type {
> > + MTK_INST_DECODER = 0,
> > + MTK_INST_ENCODER = 1,
> > +};
> > +
> > +/**
> > + * enum mtk_instance_state - The state of an MTK Vcodec instance.
> > + * @MTK_STATE_FREE - default state when instance create
> > + * @MTK_STATE_CREATE - vdec instance is create
> > + * @MTK_STATE_INIT - vdec instance is init
> > + * @MTK_STATE_CONFIG - reserved for encoder
> > + * @MTK_STATE_HEADER - vdec had sps/pps header parsed
> > + * @MTK_STATE_RUNNING - vdec is decoding
> > + * @MTK_STATE_FLUSH - vdec is flushing
> > + * @MTK_STATE_RES_CHANGE - vdec detect resolution change
> > + * @MTK_STATE_FINISH - ctx instance is stopped streaming
> > + * @MTK_STATE_DEINIT - before release ctx instance
> > + * @MTK_STATE_ERROR - vdec has something wrong
> > + * @MTK_STATE_ABORT - abort work in working thread
> > + */
> > +enum mtk_instance_state {
> > + MTK_STATE_FREE = 0,
> > + MTK_STATE_CREATE = (1 << 0),
> > + MTK_STATE_INIT = (1 << 1),
> > + MTK_STATE_CONFIG = (1 << 2),
> > + MTK_STATE_HEADER = (1 << 3),
> > + MTK_STATE_RUNNING = (1 << 4),
> > + MTK_STATE_FLUSH = (1 << 5),
> > + MTK_STATE_RES_CHANGE = (1 << 6),
> > + MTK_STATE_FINISH = (1 << 7),
> > + MTK_STATE_DEINIT = (1 << 8),
> > + MTK_STATE_ERROR = (1 << 9),
> > + MTK_STATE_ABORT = (1 << 10),
>
> This looks like it started as a state machine and somehow turned into
> flags, resulting in a state machine with 2048 states or, to give it a
> different name, a debugging nightmare.
>
It's define some state happened rather than state machine.
Though some states are for v4l2 decoder driver and not used in encoder
driver.

> If the start streaming operation implemented cleanup-on-error properly
> then there would only be two useful states: Started and stopped. Even
> the "sticky" error behavior looks unnecessary to me (meaning we don't
> need to track its state).
>
We cannot guaranteed that IOCTLs called from the user space follow
required sequence.
We need states to know if our driver could accept IOCTL command.

>
> > diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_enc.c b/drivers/media/platform/mtk-vcodec/mtk_vcodec_enc.c
> > new file mode 100644
> > index 0000000..8e1b6f0
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_enc.c
> > @@ -0,0 +1,1773 @@
> > [...]
> > +static int vb2ops_venc_start_streaming(struct vb2_queue *q, unsigned int count)
> > +{
> > + struct mtk_vcodec_ctx *ctx = vb2_get_drv_priv(q);
> > + struct v4l2_device *v4l2_dev = &ctx->dev->v4l2_dev;
> > + int ret;
> > +#if MTK_V4L2_BENCHMARK
> > + struct timeval begin, end;
> > +
> > + do_gettimeofday(&begin);
> > +#endif
> > +
> > + if (!(vb2_start_streaming_called(&ctx->m2m_ctx->out_q_ctx.q) &
> > + vb2_start_streaming_called(&ctx->m2m_ctx->cap_q_ctx.q))) {
> > + mtk_v4l2_debug(1, "[%d]-> out=%d cap=%d",
> > + ctx->idx,
> > + vb2_start_streaming_called(&ctx->m2m_ctx->out_q_ctx.q),
> > + vb2_start_streaming_called(&ctx->m2m_ctx->cap_q_ctx.q));
> > + return 0;
> > + }
> > +
> > + if ((ctx->state & (MTK_STATE_ERROR | MTK_STATE_ABORT)))
> > + return -EINVAL;
>
> This is the sort of thing I mean.
>
> This sticky error behaviour means that every subsequent call to
> vb2ops_venc_start_streaming() will fail. Note also that the user will
> never try to stop streaming (which can clear the error state) because
> according to the return code it got when it tried to start streaming we
> never actually started.
>
> This is what I mean about having two many states. From the user's
> perspective there are only two states. There needs to be a good reason
> for the driver to manage so many extra secret states internally.
>
For my understanding, that vb2ops_venc_start_streaming cannot fail.
If it fail, user space will close and release this encoder instance
(fd).
We really need to state driver to see what it should do when receive
current IOCTL.

>
> > +
> > + if (ctx->state == MTK_STATE_FREE) {
> > + ret = venc_if_create(ctx,
> > + ctx->q_data[MTK_Q_DATA_DST].fmt->fourcc,
> > + &ctx->h_enc);
> > +
> > + if (ret != 0) {
> > + ctx->state |= MTK_STATE_ERROR;
> > + v4l2_err(v4l2_dev, "invalid codec type=%x\n",
> > + ctx->q_data[MTK_Q_DATA_DST].fmt->fourcc);
> > + v4l2_err(v4l2_dev, "venc_if_create failed=%d\n", ret);
> > + return -EINVAL;
> > + }
> > +
> > + if (ctx->q_data[MTK_Q_DATA_DST].fmt->fourcc ==
> > + V4L2_PIX_FMT_H264)
> > + ctx->hdr = 1;
> > +
> > + ctx->state |= MTK_STATE_CREATE;
> > + }
> > +
> > + if ((ctx->state & MTK_STATE_CREATE) && !(ctx->state & MTK_STATE_INIT)) {
> > + ret = venc_if_init(ctx->h_enc);
> > + if (ret != 0) {
> > + ctx->state |= MTK_STATE_ERROR;
> > + v4l2_err(v4l2_dev, "venc_if_init failed=%d\n", ret);
> > + return -EINVAL;
>
> This error path leaves the encoder partially constructed and relies on
> something else to tidy things up. It would be much better to tidy things
> up from this function and
>
> Also I don't think both venc_if_create and venc_if_init are needed. They
> are only ever called one after the other and thus they only serve to
> complicate the error handling code.
>
venc_if_create is for creating instance in arm side and base on encode
format hook corresponding encoder driver interface.
venc_if_init is trying to init encoder instance in VPU side.
Failures from two functions should have different error handling.
We will enhance this part in next version.

>
> > diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_util.h b/drivers/media/platform/mtk-vcodec/mtk_vcodec_util.h
> > new file mode 100644
> > index 0000000..a8e683a
> > --- /dev/null
> > +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_util.h
> > @@ -0,0 +1,66 @@
> > +/*
> > +* Copyright (c) 2015 MediaTek Inc.
> > +* Author: PC Chen <pc.chen@mediatek.com>
> > +* Tiffany Lin <tiffany.lin@mediatek.com>
> > +*
> > +* This program is free software; you can redistribute it and/or modify
> > +* it under the terms of the GNU General Public License version 2 as
> > +* published by the Free Software Foundation.
> > +*
> > +* This program is distributed in the hope that it will be useful,
> > +* but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > +* GNU General Public License for more details.
> > +*/
> > +
> > +#ifndef _MTK_VCODEC_UTIL_H_
> > +#define _MTK_VCODEC_UTIL_H_
> > +
> > +#include <linux/types.h>
> > +#include <linux/dma-direction.h>
> > +
> > +struct mtk_vcodec_mem {
> > + size_t size;
> > + void *va;
> > + dma_addr_t dma_addr;
> > +};
> > +
> > +extern int mtk_v4l2_dbg_level;
> > +extern bool mtk_vcodec_dbg;
> > +
> > +#define mtk_v4l2_debug(level, fmt, args...) \
> > + do { \
> > + if (mtk_v4l2_dbg_level >= level) \
> > + pr_info("[MTK_V4L2] level=%d %s(),%d: " fmt "\n",\
> > + level, __func__, __LINE__, ##args); \
> > + } while (0)
> > +
> > +#define mtk_v4l2_err(fmt, args...) \
> > + pr_err("[MTK_V4L2][ERROR] %s:%d: " fmt "\n", __func__, __LINE__, \
> > + ##args)
>
> Obviously the code should be structured to make use of dev_dbg/dev_err
> possible.
>
> However where this won't work do you really need special macros for
> this. Assuming your error messages are well written 'git grep' and the
> following should be enough:
>
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
Thanks.
For pr_err case, we will try to use "#define pr_fmt(fmt) KBUILD_MODNAME
": " fmt" in next version.
For pr_info case, we still need debug level to control output messages.

>
> > +#define mtk_v4l2_debug_enter() mtk_v4l2_debug(5, "+\n")
> > +#define mtk_v4l2_debug_leave() mtk_v4l2_debug(5, "-\n")
>
> Remove these. If you care about function entry and exit for debugging
> you should be able to use ftrace.
>
I am not familiar with ftrace.
What if we only want to trace v4l2 video encoder driver called flow not
called stack? And only for functions we are interested not all
functions.
I will check if it is convenience for us using ftrace.

>
> > +#define mtk_vcodec_debug(h, fmt, args...) \
> > + do { \
> > + if (mtk_vcodec_dbg) \
> > + pr_info("[MTK_VCODEC][%d]: %s() " fmt "\n", \
> > + ((struct mtk_vcodec_ctx *)h->ctx)->idx, \
> > + __func__, ##args); \
> > + } while (0)
> > +
> > +#define mtk_vcodec_err(h, fmt, args...) \
> > + pr_err("[MTK_VCODEC][ERROR][%d]: %s() " fmt "\n", \
> > + ((struct mtk_vcodec_ctx *)h->ctx)->idx, __func__, ##args)
> > +
> > +#define mtk_vcodec_debug_enter(h) mtk_vcodec_debug(h, "+\n")
> > +#define mtk_vcodec_debug_leave(h) mtk_vcodec_debug(h, "-\n")
>
> All above comments apply to these too.
>

best regards,
Tiffany