Message-ID: <20211112103007.GB27562@kadam>
Date:   Fri, 12 Nov 2021 13:30:07 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
Cc:     linux-media@...r.kernel.org,
        Robert Beckett <bob.beckett@...labora.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:STAGING SUBSYSTEM" <linux-staging@...ts.linux.dev>,
        open list <linux-kernel@...r.kernel.org>,
        laurent.pinchart@...asonboard.com, hverkuil@...all.nl,
        kernel@...labora.com, dafna3@...il.com,
        kiril.bicevski@...labora.com,
        Nas Chung <nas.chung@...psnmedia.com>,
        lafley.kim@...psnmedia.com, scott.woo@...psnmedia.com,
        olivier.crete@...labora.com, rdunlap@...radead.org
Subject: Re: [PATCH v3 2/6] staging: media: wave5: Add the vdi layer


Why are normal kernel endianness/__swab32 routines not sufficient?

On Wed, Nov 10, 2021 at 02:09:06PM +0200, Dafna Hirschfeld wrote:
> Add the vdi directory of the wave5 codec driver.
> The vdi.h header defines common helper functions
> such as writing/reading register and handling endianness.
> 
> Signed-off-by: Robert Beckett <bob.beckett@...labora.com>
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
> ---
>  drivers/staging/media/wave5/vdi.c | 260 ++++++++++++++++++++++++++++++
>  drivers/staging/media/wave5/vdi.h |  76 +++++++++
>  2 files changed, 336 insertions(+)
>  create mode 100644 drivers/staging/media/wave5/vdi.c
>  create mode 100644 drivers/staging/media/wave5/vdi.h
> 
> diff --git a/drivers/staging/media/wave5/vdi.c b/drivers/staging/media/wave5/vdi.c
> new file mode 100644
> index 000000000000..6049ef76c948
> --- /dev/null
> +++ b/drivers/staging/media/wave5/vdi.c
> @@ -0,0 +1,260 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +/*
> + * Wave5 series multi-standard codec IP - low level access functions
> + *
> + * Copyright (C) 2021 CHIPS&MEDIA INC
> + */
> +#include <linux/bug.h>
> +#include "vdi.h"
> +#include "vpu.h"
> +#include "wave5_regdefine.h"
> +#include <linux/delay.h>
> +#define VDI_SRAM_BASE_ADDR 0x00
> +
> +#define VDI_SYSTEM_ENDIAN VDI_LITTLE_ENDIAN
> +#define VDI_128BIT_BUS_SYSTEM_ENDIAN VDI_128BIT_LITTLE_ENDIAN
> +
> +static int wave5_vdi_allocate_common_memory(struct device *dev)
> +{
> +	int ret;
> +	struct vpu_device *vpu_dev = dev_get_drvdata(dev);
> +
> +	if (!vpu_dev->common_mem.vaddr) {
> +		vpu_dev->common_mem.size = SIZE_COMMON;
> +		ret = wave5_vdi_allocate_dma_memory(vpu_dev, &vpu_dev->common_mem);
> +		if (ret) {
> +			dev_err(dev, "unable to allocate common buffer\n");
> +			return ret;
> +		}
> +	}
> +
> +	dev_dbg(dev, "common_mem: daddr=%pad size=%zu vaddr=0x%p\n",
> +		&vpu_dev->common_mem.daddr, vpu_dev->common_mem.size,
> +			vpu_dev->common_mem.vaddr);
> +
> +	return 0;
> +}
> +
> +int wave5_vdi_init(struct device *dev)
> +{
> +	struct vpu_device *vpu_dev = dev_get_drvdata(dev);
> +	int i;
> +	int ret;
> +
> +	ret = wave5_vdi_allocate_common_memory(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "[VDI] fail to get vpu common buffer from driver\n");
> +		return ret;
> +	}
> +
> +	if (PRODUCT_CODE_W_SERIES(vpu_dev->product_code)) {
> +		// if BIT processor is not running.
> +		if (wave5_vdi_read_register(vpu_dev, W5_VCPU_CUR_PC) == 0) {
> +			for (i = 0; i < 64; i++)
> +				wave5_vdi_write_register(vpu_dev, (i * 4) + 0x100, 0x0);
> +		}
> +	} else {
> +		WARN_ONCE(1, "unsupported product code 0x%x\n", vpu_dev->product_code);
> +	}
> +
> +	dev_dbg(dev, "[VDI] success to init driver\n");
> +
> +	return 0;
> +
> +	wave5_vdi_release(dev);
> +	return ret;

Delete this dead code.

> +}
> +
> +int wave5_vdi_release(struct device *dev)
> +{
> +	struct vpu_device *vpu_dev = dev_get_drvdata(dev);
> +
> +	memset(&vpu_dev->vdb_register, 0x00, sizeof(vpu_dev->vdb_register));
> +	wave5_vdi_free_dma_memory(vpu_dev, &vpu_dev->common_mem);
> +
> +	return 0;
> +}
> +
> +void wave5_vdi_write_register(struct vpu_device *vpu_dev, unsigned int addr, unsigned int data)
> +{
> +	writel(data, vpu_dev->vdb_register.vaddr + addr);
> +}
> +
> +unsigned int wave5_vdi_read_register(struct vpu_device *vpu_dev, unsigned int addr)
> +{
> +	return readl(vpu_dev->vdb_register.vaddr + addr);
> +}
> +
> +int wave5_vdi_clear_memory(struct vpu_device *vpu_dev, struct vpu_buf *vb)
> +{
> +	if (!vb || !vb->vaddr) {
> +		dev_err(vpu_dev->dev, "%s(): unable to clear unmapped buffer\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	memset(vb->vaddr, 0, vb->size);
> +	return vb->size;
> +}
> +
> +static int wave5_swap_endian(struct vpu_device *vpu_dev, u8 *data, int len, int endian);
> +
> +int wave5_vdi_write_memory(struct vpu_device *vpu_dev, struct vpu_buf *vb, size_t offset,
> +			   u8 *data, int len, int endian)
> +{
> +	if (!vb || !vb->vaddr) {
> +		dev_err(vpu_dev->dev, "%s(): unable to write to unmapped buffer\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	if ((offset + len) > vb->size) {

I wish there were an integer overflow check on this.

	if (offset > vb->size || len > vb->size || offset + len > vb->size) {


> +		dev_err(vpu_dev->dev, "%s(): buffer too small\n", __func__);
> +		return -ENOSPC;
> +	}
> +
> +	wave5_swap_endian(vpu_dev, data, len, endian);
> +	memcpy(vb->vaddr + offset, data, len);
> +
> +	return len;
> +}
> +
> +int wave5_vdi_allocate_dma_memory(struct vpu_device *vpu_dev, struct vpu_buf *vb)
> +{
> +	void *vaddr;
> +	dma_addr_t daddr;
> +
> +	if (!vb->size) {
> +		dev_err(vpu_dev->dev, "%s(): requested size==0\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	vaddr = dma_alloc_coherent(vpu_dev->dev, vb->size, &daddr, GFP_KERNEL);
> +	if (!vaddr)
> +		return -ENOMEM;
> +	vb->vaddr = vaddr;
> +	vb->daddr = daddr;
> +
> +	return 0;
> +}
> +
> +void wave5_vdi_free_dma_memory(struct vpu_device *vpu_dev, struct vpu_buf *vb)
> +{
> +	if (vb->size == 0)
> +		return;
> +
> +	if (!vb->vaddr)
> +		dev_err(vpu_dev->dev, "%s(): requested free of unmapped buffer\n", __func__);
> +	else
> +		dma_free_coherent(vpu_dev->dev, vb->size, vb->vaddr, vb->daddr);
> +
> +	memset(vb, 0, sizeof(*vb));
> +}
> +
> +int wave5_vdi_convert_endian(struct vpu_device *vpu_dev, unsigned int endian)
> +{
> +	if (PRODUCT_CODE_W_SERIES(vpu_dev->product_code)) {
> +		switch (endian) {
> +		case VDI_LITTLE_ENDIAN:
> +			endian = 0x00;
> +			break;
> +		case VDI_BIG_ENDIAN:
> +			endian = 0x0f;
> +			break;
> +		case VDI_32BIT_LITTLE_ENDIAN:
> +			endian = 0x04;
> +			break;
> +		case VDI_32BIT_BIG_ENDIAN:
> +			endian = 0x03;
> +			break;
> +		}
> +	}
> +
> +	return (endian & 0x0f);
> +}
> +
> +static void byte_swap(unsigned char *data, int len)
> +{
> +	u8 temp;
> +	s32 i;

s32 is only for hardware specs.  Use int.

> +
> +	for (i = 0; i < len; i += 2) {
> +		temp = data[i];
> +		data[i] = data[i + 1];
> +		data[i + 1] = temp;
> +	}
> +}
> +
> +static void word_swap(unsigned char *data, int len)
> +{
> +	u16 temp;
> +	u16 *ptr = (uint16_t *)data;
> +	s32 i, size = len / (int)sizeof(uint16_t);

No need for this cast.

> +
> +	for (i = 0; i < size; i += 2) {
> +		temp = ptr[i];
> +		ptr[i] = ptr[i + 1];
> +		ptr[i + 1] = temp;
> +	}
> +}
> +
> +static void dword_swap(unsigned char *data, int len)
> +{
> +	u32 temp;
> +	u32 *ptr = (uint32_t *)data;

u32 * on both sides of the assign.

> +	s32 i, size = len / (int)sizeof(uint32_t);
> +
> +	for (i = 0; i < size; i += 2) {
> +		temp = ptr[i];
> +		ptr[i] = ptr[i + 1];
> +		ptr[i + 1] = temp;
> +	}
> +}
> +
> +static void lword_swap(unsigned char *data, int len)
> +{
> +	u64 temp;
> +	u64 *ptr = (uint64_t *)data;
> +	s32 i, size = len / (int)sizeof(uint64_t);
> +
> +	for (i = 0; i < size; i += 2) {
> +		temp = ptr[i];
> +		ptr[i] = ptr[i + 1];
> +		ptr[i + 1] = temp;
> +	}
> +}
> +
> +static int wave5_swap_endian(struct vpu_device *vpu_dev, u8 *data, int len, int endian)
> +{
> +	int changes;
> +	int sys_endian;
> +	bool byte_change, word_change, dword_change, lword_change;
> +
> +	if (PRODUCT_CODE_W_SERIES(vpu_dev->product_code)) {
> +		sys_endian = VDI_128BIT_BUS_SYSTEM_ENDIAN;
> +	} else {
> +		dev_err(vpu_dev->dev, "unknown product id : %08x\n", vpu_dev->product_code);
> +		return -1;

Use proper error codes.  Except no one cares about the error codes so
just make it void.

> +	}
> +
> +	endian = wave5_vdi_convert_endian(vpu_dev, endian);
> +	sys_endian = wave5_vdi_convert_endian(vpu_dev, sys_endian);
> +	if (endian == sys_endian)
> +		return 0;
> +
> +	changes = endian ^ sys_endian;
> +	byte_change = changes & 0x01;
> +	word_change = ((changes & 0x02) == 0x02);
> +	dword_change = ((changes & 0x04) == 0x04);
> +	lword_change = ((changes & 0x08) == 0x08);
> +
> +	if (byte_change)
> +		byte_swap(data, len);
> +	if (word_change)
> +		word_swap(data, len);
> +	if (dword_change)
> +		dword_swap(data, len);
> +	if (lword_change)
> +		lword_swap(data, len);
> +
> +	return 1;

If you decide to go this route, add a comment at the top of the function
explaining the return codes.

> +}

regards,
dan carpenter

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