[U-Boot] [PATCH v5 2/2] common: Generic firmware loader for file system

[Chee, Tien Fong <tien.fong.chee@intel.com>]

On Jum, 2017-12-22 at 09:47 +0100, Lothar Waßmann wrote:
> Hi,
> 
> On Fri, 22 Dec 2017 08:04:32 +0000 Chee, Tien Fong wrote:
> > 
> > On Jum, 2017-12-22 at 08:44 +0100, Lothar Waßmann wrote:
> > > 
> > > Hi,
> > > 
> > > On Fri, 22 Dec 2017 01:43:38 +0000 Chee, Tien Fong wrote:
> > > > 
> > > > 
> > > > On Kha, 2017-12-21 at 16:08 +0100, Lothar Waßmann wrote:
> > > > > 
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > On Thu, 21 Dec 2017 12:48:53 +0000 Chee, Tien Fong wrote:
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > On Kha, 2017-12-21 at 12:53 +0100, Lothar Waßmann wrote:
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > Hi,
> > > > > > > 
> > > > > > > On Thu, 21 Dec 2017 09:36:41 +0000 Chee, Tien Fong wrote:
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > On Kha, 2017-12-21 at 09:48 +0100, Lothar Waßmann
> > > > > > > > wrote:
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > Hi,
> > > > > > > > > 
> > > > > > > > > On Thu, 21 Dec 2017 15:25:29 +0800 tien.fong.chee at int
> > > > > > > > > el.c
> > > > > > > > > om
> > > > > > > > > wrote:
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > From: Tien Fong Chee <tien.fong.chee@intel.com>
> > > > > > > > > > 
> > > > > > > > > > This is file system generic loader which can be
> > > > > > > > > > used to
> > > > > > > > > > load
> > > > > > > > > > the file image from the storage into target such as
> > > > > > > > > > memory.
> > > > > > > > > > The consumer driver would then use this loader to
> > > > > > > > > > program
> > > > > > > > > > whatever,
> > > > > > > > > > ie. the FPGA device.
> > > > > > > > > > 
> > > > > > > > > > Signed-off-by: Tien Fong Chee <tien.fong.chee@intel
> > > > > > > > > > .com
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > ---
> > > > > > > > > >  common/Makefile            |   1 +
> > > > > > > > > >  common/fs_loader.c         | 311
> > > > > > > > > > +++++++++++++++++++++++++++++++++++++++++++++
> > > > > > > > > >  doc/README.firmware_loader |  76 +++++++++++
> > > > > > > > > >  include/fs_loader.h        |  28 ++++
> > > > > > > > > >  4 files changed, 416 insertions(+)
> > > > > > > > > >  create mode 100644 common/fs_loader.c
> > > > > > > > > >  create mode 100644 doc/README.firmware_loader
> > > > > > > > > >  create mode 100644 include/fs_loader.h
> > > > > > > > > > 
> > > > > > > > > > diff --git a/common/Makefile b/common/Makefile
> > > > > > > > > > index cec506f..2934221 100644
> > > > > > > > > > --- a/common/Makefile
> > > > > > > > > > +++ b/common/Makefile
> > > > > > > > > > @@ -130,3 +130,4 @@ obj-$(CONFIG_CMD_DFU) += dfu.o
> > > > > > > > > >  obj-y += command.o
> > > > > > > > > >  obj-y += s_record.o
> > > > > > > > > >  obj-y += xyzModem.o
> > > > > > > > > > +obj-y += fs_loader.o
> > > > > > > > > > diff --git a/common/fs_loader.c
> > > > > > > > > > b/common/fs_loader.c
> > > > > > > > > > new file mode 100644
> > > > > > > > > > index 0000000..ddfce58
> > > > > > > > > > --- /dev/null
> > > > > > > > > > +++ b/common/fs_loader.c
> > > > > > > > > > @@ -0,0 +1,311 @@
> > > > > > > > > > +/*
> > > > > > > > > > + * Copyright (C) 2017 Intel Corporation <www.intel
> > > > > > > > > > .com
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > + *
> > > > > > > > > > + * SPDX-License-Identifier:    GPL-2.0
> > > > > > > > > > + */
> > > > > > > > > > +
> > > > > > > > > > +#include <common.h>
> > > > > > > > > > +#include <errno.h>
> > > > > > > > > > +#include <fs.h>
> > > > > > > > > > +#include <fs_loader.h>
> > > > > > > > > > +#include <nand.h>
> > > > > > > > > > +#include <sata.h>
> > > > > > > > > > +#include <spi.h>
> > > > > > > > > > +#include <spi_flash.h>
> > > > > > > > > > +#include <spl.h>
> > > > > > > > > > +#include <linux/string.h>
> > > > > > > > > > +#include <usb.h>
> > > > > > > > > > +
> > > > > > > > > > +struct firmware_priv {
> > > > > > > > > > +	const char *name;	/* Filename */
> > > > > > > > > > +	u32 offset;		/* Offset of
> > > > > > > > > > reading a
> > > > > > > > > > file
> > > > > > > > > > */
> > > > > > > > > > +};
> > > > > > > > > > +
> > > > > > > > > > +static struct device_location default_locations[]
> > > > > > > > > > = {
> > > > > > > > > > +	{
> > > > > > > > > > +		.name = "mmc",
> > > > > > > > > > +		.devpart = "0:1",
> > > > > > > > > > +	},
> > > > > > > > > > +	{
> > > > > > > > > > +		.name = "usb",
> > > > > > > > > > +		.devpart = "0:1",
> > > > > > > > > > +	},
> > > > > > > > > > +	{
> > > > > > > > > > +		.name = "sata",
> > > > > > > > > > +		.devpart = "0:1",
> > > > > > > > > > +	},
> > > > > > > > > > +};
> > > > > > > > > > +
> > > > > > > > > > +/* USB build is not supported yet in SPL */
> > > > > > > > > > +#ifndef CONFIG_SPL_BUILD
> > > > > > > > > > +#ifdef CONFIG_USB_STORAGE
> > > > > > > > > > +static int init_usb(void)
> > > > > > > > > > +{
> > > > > > > > > > +	int err;
> > > > > > > > > > +
> > > > > > > > > > +	err = usb_init();
> > > > > > > > > > +	if (err)
> > > > > > > > > > +		return err;
> > > > > > > > > > +
> > > > > > > > > > +#ifndef CONFIG_DM_USB
> > > > > > > > > > +	err = usb_stor_scan(1) < 0 ? -ENODEV : 0;
> > > > > > > > > > +#endif
> > > > > > > > > > +
> > > > > > > > > > +	return err;
> > > > > > > > > > +}
> > > > > > > > > > +#else
> > > > > > > > > > +static int init_usb(void)
> > > > > > > > > > +{
> > > > > > > > > > +	printf("Error: Cannot load flash image: no
> > > > > > > > > > USB
> > > > > > > > > > support\n");
> > > > > > > > > > +	return -ENOSYS;
> > > > > > > > > > +}
> > > > > > > > > > +#endif
> > > > > > > > > > +#endif
> > > > > > > > > > +
> > > > > > > > > > +#ifdef CONFIG_SATA
> > > > > > > > > > +static int init_storage_sata(void)
> > > > > > > > > > +{
> > > > > > > > > > +	return sata_probe(0);
> > > > > > > > > > +}
> > > > > > > > > > +#else
> > > > > > > > > > +static int init_storage_sata(void)
> > > > > > > > > > +{
> > > > > > > > > > +	printf("Error: Cannot load image: no SATA
> > > > > > > > > > support\n");
> > > > > > > > > > +	return -ENOSYS;
> > > > > > > > > > +}
> > > > > > > > > > +#endif
> > > > > > > > > > +
> > > > > > > > > > +#ifdef CONFIG_CMD_UBIFS
> > > > > > > > > > +static int mount_ubifs(struct device_location
> > > > > > > > > > *location)
> > > > > > > > > > +{
> > > > > > > > > > +	int ret;
> > > > > > > > > > +	char cmd[32];
> > > > > > > > > > +
> > > > > > > > > > +	sprintf(cmd, "ubi part %s", location-
> > > > > > > > > > > 
> > > > > > > > > > > mtdpart);
> > > > > > > > > > +
> > > > > > > > > > +	ret = run_command(cmd, 0);
> > > > > > > > > > +	if (ret)
> > > > > > > > > > +		return ret;
> > > > > > > > > > +
> > > > > > > > > > +	sprintf(cmd, "ubifsmount %s", location-
> > > > > > > > > > > 
> > > > > > > > > > > ubivol);
> > > > > > > > > > +
> > > > > > > > > > +	ret = run_command(cmd, 0);
> > > > > > > > > > +
> > > > > > > > > > +	return ret;
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > +static int umount_ubifs(void)
> > > > > > > > > > +{
> > > > > > > > > > +	return run_command("ubifsumount", 0);
> > > > > > > > > > +}
> > > > > > > > > > +#else
> > > > > > > > > > +static int mount_ubifs(struct device_location
> > > > > > > > > > *location)
> > > > > > > > > > +{
> > > > > > > > > > +	printf("Error: Cannot load image: no UBIFS
> > > > > > > > > > support\n");
> > > > > > > > > > +	return -ENOSYS;
> > > > > > > > > > +}
> > > > > > > > > > +#endif
> > > > > > > > > > +
> > > > > > > > > > +#if defined(CONFIG_SPL_MMC_SUPPORT) &&
> > > > > > > > > > defined(CONFIG_SPL_BUILD)
> > > > > > > > > > +static int init_mmc(void)
> > > > > > > > > > +{
> > > > > > > > > > +	/* Just for the case MMC is not yet
> > > > > > > > > > initialized */
> > > > > > > > > > +	struct mmc *mmc = NULL;
> > > > > > > > > > +	int err;
> > > > > > > > > > +
> > > > > > > > > > +	spl_mmc_find_device(&mmc,
> > > > > > > > > > spl_boot_device());
> > > > > > > > > > +
> > > > > > > > > > +	err = mmc_init(mmc);
> > > > > > > > > > +	if (err) {
> > > > > > > > > > +		printf("spl: mmc init failed with
> > > > > > > > > > error:
> > > > > > > > > > %d\n",
> > > > > > > > > > err);
> > > > > > > > > > +		return err;
> > > > > > > > > > +	}
> > > > > > > > > > +
> > > > > > > > > > +	return err;
> > > > > > > > > > +}
> > > > > > > > > > +#else
> > > > > > > > > > +static int init_mmc(void)
> > > > > > > > > > +{
> > > > > > > > > > +	/* Expect somewhere already initialize MMC
> > > > > > > > > > */
> > > > > > > > > > +	return 0;
> > > > > > > > > > +}
> > > > > > > > > > +#endif
> > > > > > > > > > +
> > > > > > > > > > +static int select_fs_dev(struct device_location
> > > > > > > > > > *location)
> > > > > > > > > > +{
> > > > > > > > > > +	int ret;
> > > > > > > > > > +
> > > > > > > > > > +	if (!strcmp("mmc", location->name)) {
> > > > > > > > > > +		ret = fs_set_blk_dev("mmc",
> > > > > > > > > > location-
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > devpart,
> > > > > > > > > > FS_TYPE_ANY);
> > > > > > > > > > +	} else if (!strcmp("usb", location->name)) 
> > > > > > > > > > {
> > > > > > > > > > +		ret = fs_set_blk_dev("usb",
> > > > > > > > > > location-
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > devpart,
> > > > > > > > > > FS_TYPE_ANY);
> > > > > > > > > > +	} else if (!strcmp("sata", location-
> > > > > > > > > > >name)) {
> > > > > > > > > > +		ret = fs_set_blk_dev("sata",
> > > > > > > > > > location-
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > devpart,
> > > > > > > > > > FS_TYPE_ANY);
> > > > > > > > > > +	} else if (!strcmp("ubi", location->name)) 
> > > > > > > > > > {
> > > > > > > > > > +		if (location->ubivol != NULL)
> > > > > > > > > > +			ret =
> > > > > > > > > > fs_set_blk_dev("ubi",
> > > > > > > > > > NULL,
> > > > > > > > > > FS_TYPE_UBIFS);
> > > > > > > > > > +		else
> > > > > > > > > > +			ret = -ENODEV;
> > > > > > > > > > +	} else {
> > > > > > > > > > +		printf("Error: unsupported
> > > > > > > > > > location
> > > > > > > > > > storage.\n");
> > > > > > > > > > +		return -ENODEV;
> > > > > > > > > > +	}
> > > > > > > > > > +
> > > > > > > > > > +	if (ret)
> > > > > > > > > > +		printf("Error: could not access
> > > > > > > > > > storage.\n");
> > > > > > > > > > +
> > > > > > > > > > +	return ret;
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > +static int init_storage_device(struct
> > > > > > > > > > device_location
> > > > > > > > > > *location)
> > > > > > > > > > +{
> > > > > > > > > > +	int ret;
> > > > > > > > > > +
> > > > > > > > > > +	if (!strcmp("mmc", location->name)) {
> > > > > > > > > > +		ret = init_mmc();
> > > > > > > > > > +	} else if (!strcmp("sata", location-
> > > > > > > > > > >name)) {
> > > > > > > > > > +		ret = init_storage_sata();
> > > > > > > > > > +	} else if (location->ubivol != NULL) {
> > > > > > > > > > +		ret = mount_ubifs(location);
> > > > > > > > > > +#ifndef CONFIG_SPL_BUILD
> > > > > > > > > > +	/* USB build is not supported yet in SPL
> > > > > > > > > > */
> > > > > > > > > > +	} else if (!strcmp("usb", location->name)) 
> > > > > > > > > > {
> > > > > > > > > > +		ret = init_usb();
> > > > > > > > > > +#endif
> > > > > > > > > > +	} else {
> > > > > > > > > > +		printf("Error: no supported
> > > > > > > > > > storage
> > > > > > > > > > device
> > > > > > > > > > is
> > > > > > > > > > available.\n");
> > > > > > > > > > +		ret = -ENODEV;
> > > > > > > > > > +	}
> > > > > > > > > > +
> > > > > > > > > > +	return ret;
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > +static void set_storage_devpart(char *name, char
> > > > > > > > > > *devpart)
> > > > > > > > > > +{
> > > > > > > > > > +	size_t i;
> > > > > > > > > > +
> > > > > > > > > > +	for (i = 0; i <
> > > > > > > > > > ARRAY_SIZE(default_locations);
> > > > > > > > > > i++) {
> > > > > > > > > > +		if
> > > > > > > > > > (!strcmp(default_locations[i].name,
> > > > > > > > > > name))
> > > > > > > > > > +			default_locations[i].devpa
> > > > > > > > > > rt =
> > > > > > > > > > devpart;
> > > > > > > > > > +	}
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > +/*
> > > > > > > > > > + * Prepare firmware struct;
> > > > > > > > > > + * return -ve if fail.
> > > > > > > > > > + */
> > > > > > > > > > +static int _request_firmware_prepare(struct
> > > > > > > > > > firmware
> > > > > > > > > > **firmware_p,
> > > > > > > > > > +				     const char
> > > > > > > > > > *name,
> > > > > > > > > > void
> > > > > > > > > > *dbuf,
> > > > > > > > > > +				     size_t size,
> > > > > > > > > > u32
> > > > > > > > > > offset)
> > > > > > > > > > +{
> > > > > > > > > > +	struct firmware *firmware;
> > > > > > > > > > +	struct firmware_priv *fw_priv;
> > > > > > > > > > +
> > > > > > > > > > +	*firmware_p = NULL;
> > > > > > > > > > +
> > > > > > > > > > +	if (!name || name[0] == '\0')
> > > > > > > > > > +		return -EINVAL;
> > > > > > > > > > +
> > > > > > > > > > +	firmware = calloc(1, sizeof(*firmware));
> > > > > > > > > > +	if (!firmware) {
> > > > > > > > > > +		printf("%s: calloc(struct
> > > > > > > > > > firmware)
> > > > > > > > > > failed\n",
> > > > > > > > > > __func__);
> > > > > > > > > > +		return -ENOMEM;
> > > > > > > > > > +	}
> > > > > > > > > > +
> > > > > > > > > > +	fw_priv = calloc(1, sizeof(*fw_priv));
> > > > > > > > > > +	if (!fw_priv) {
> > > > > > > > > > +		printf("%s: calloc(struct fw_priv)
> > > > > > > > > > failed\n",
> > > > > > > > > > __func__);
> > > > > > > > > > +		free(firmware);
> > > > > > > > > > +		return -ENOMEM;
> > > > > > > > > > +	}
> > > > > > > > > > +
> > > > > > > > > > +	fw_priv->name = name;
> > > > > > > > > > +	fw_priv->offset = offset;
> > > > > > > > > > +	firmware->data = dbuf;
> > > > > > > > > > +	firmware->size = size;
> > > > > > > > > > +	firmware->priv = fw_priv;
> > > > > > > > > > +	*firmware_p = firmware;
> > > > > > > > > > +
> > > > > > > > > > +	return 0;
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > +/*
> > > > > > > > > > + * fw_get_filesystem_firmware - load firmware into
> > > > > > > > > > an
> > > > > > > > > > allocated
> > > > > > > > > > buffer
> > > > > > > > > > + * @location: An array of supported firmware
> > > > > > > > > > location
> > > > > > > > > > + * @firmware_p: pointer to firmware image
> > > > > > > > > > + *
> > > > > > > > > > + * @return: size of total read
> > > > > > > > > > + *	    -ve when error
> > > > > > > > > > + */
> > > > > > > > > > +static int fw_get_filesystem_firmware(struct
> > > > > > > > > > device_location
> > > > > > > > > > *location,
> > > > > > > > > > +				      struct
> > > > > > > > > > firmware
> > > > > > > > > > *firmware_p)
> > > > > > > > > > +{
> > > > > > > > > > +	struct firmware_priv *fw_priv = NULL;
> > > > > > > > > > +	loff_t actread;
> > > > > > > > > > +	char *dev_part;
> > > > > > > > > > +	int ret;
> > > > > > > > > > +
> > > > > > > > > > +	dev_part = env_get("fw_dev_part");
> > > > > > > > > > +	if (dev_part)
> > > > > > > > > > +		set_storage_devpart(location-
> > > > > > > > > > >name,
> > > > > > > > > > dev_part);
> > > > > > > > > > +
> > > > > > > > > > +	ret = init_storage_device(location);
> > > > > > > > > > +	if (ret)
> > > > > > > > > > +		goto out;
> > > > > > > > > > +
> > > > > > > > > > +	select_fs_dev(location);
> > > > > > > > > > 
> > > > > > > > > 'ret = ' is missing.
> > > > > > > > > 
> > > > > > > > Okay.
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > +	if (ret)
> > > > > > > > > > +		goto out;
> > > > > > > > > > +
> > > > > > > > > > +	fw_priv = firmware_p->priv;
> > > > > > > > > > +
> > > > > > > > > > +	ret = fs_read(fw_priv->name,
> > > > > > > > > > (ulong)firmware_p-
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > data,
> > > > > > > > > > fw_priv->offset,
> > > > > > > > > > +		     firmware_p->size, &actread);
> > > > > > > > > > +
> > > > > > > > > > +	if (ret) {
> > > > > > > > > > +		printf("Error: %d Failed to read
> > > > > > > > > > %s
> > > > > > > > > > from
> > > > > > > > > > flash
> > > > > > > > > > %lld != %d.\n",
> > > > > > > > > > +		      ret, fw_priv->name, actread,
> > > > > > > > > > firmware_p-
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > 
> > > > > > > > > > > size);
> > > > > > > > > > +		return ret;
> > > > > > > > > Y
> > > > > > > > > Shouldn't this be 'goto out', do do the
> > > > > > > > > umount_ubifs() as
> > > > > > > > > in
> > > > > > > > > all
> > > > > > > > > other
> > > > > > > > > error cases?
> > > > > > > > > 
> > > > > > > > okay.
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > +	} else {
> > > > > > > > > > +		ret = actread;
> > > > > > > > > > +	}
> > > > > > > > > > 
> > > > > > > > > What if actread != firmware_p->size?
> > > > > > > > > You handled it as an error before, now you happily
> > > > > > > > > return
> > > > > > > > > the
> > > > > > > > > number
> > > > > > > > > of
> > > > > > > > > bytes read in case of a short read.
> > > > > > > > > Operation not permitted
> > > > > > > > May be i misunderstand on ur previosly comment. There
> > > > > > > > is
> > > > > > > > not
> > > > > > > > much
> > > > > > > > 
> > > > > > > My comment was about returning -EPERM in this case.
> > > > > > > First of all you discarded the possible error code
> > > > > > > returned
> > > > > > > from
> > > > > > > fs_read() and secondly -EIO would be more appropriate
> > > > > > > than
> > > > > > > EPERM
> > > > > > > in
> > > > > > > case of reading less data than expected. 
> > > > > > > 
> > > > > > One of the reason I prefer to use -EIO instead of return
> > > > > > from
> > > > > > fs_read,
> > > > > > because i'm not sure when "actread != firmware_p->size",
> > > > > > the
> > > > > > return
> > > > > > from the fs_read is still -ve or not.
> > > > > > 
> > > > > The return code of fs_read() could be for example -ENOENT, if
> > > > > the
> > > > > file
> > > > > you try to load does not exist. Replacing it with -EIO will
> > > > > mislead
> > > > > users about the cause of the error.
> > > > > Thus, if fs_read()'s return code is < 0, you should return
> > > > > that!
> > > > > If it is zero and you decide to treat actread =! firmware_p-
> > > > > >size 
> > > > > as
> > > > > an
> > > > > error, you should return -EIO only in that case!
> > > > > 
> > > > Okay.
> > > > > 
> > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > 
> > > > > > > > description on fd_read, i just knowing that -ve is
> > > > > > > > error
> > > > > > > > from
> > > > > > > > function
> > > > > > > > based on other example codes in U-Boot as they check
> > > > > > > > the
> > > > > > > > error
> > > > > > > > with
> > > > > > > > "ret < 0" or "ret != 0". "actread != firmware_p->size"
> > > > > > > > is
> > > > > > > > the
> > > > > > > > additonal
> > > > > > > > checking i added myself because when i digging to the
> > > > > > > > code,
> > > > > > > > i
> > > > > > > > found
> > > > > > > > that such condition only with error printf inside the
> > > > > > > > function
> > > > > > > > without
> > > > > > > > any error code return. So, i am not sure when "actread
> > > > > > > > !=
> > > > > > > > firmware_p-
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > size", the ret would be -ve too.
> > > > > > > If 'size' is the actual size of the caller provided
> > > > > > > buffer
> > > > > > > and
> > > > > > > not
> > > > > > > the
> > > > > > > exact size of the firmware to be loaded, the condition
> > > > > > > actread !=
> > > > > > > size
> > > > > > > would not be an error at all.
> > > > > > > If 'size' designates the exact size of the firmware, that
> > > > > > > the
> > > > > > > caller
> > > > > > > may know by other means, it is obviously an error if
> > > > > > > actread
> > > > > > > !=
> > > > > > > size.
> > > > > > > Since you treated actread != size as an error in your
> > > > > > > original
> > > > > > > patch
> > > > > > > I
> > > > > > > assumed the latter case.
> > > > > > > 
> > > > > > The size here refer to the size of firmware or chunk of
> > > > > > firmware to
> > > > > > read when the buffer is smaller than firmware.
> > > > > > 
> > > > > OK. In that case, you should not print a message when actread
> > > > > !=
> > > > > firmware_p->size, since fs_read will have already printed a
> > > > > message
> > > > > due
> > > > > to this.
> > > > > 
> > > > The printed message with additional info such as ret, size and
> > > > actread.
> > > > > 
> > > > > 
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > AFAICT Linux uses the first semantics ('size' specifies
> > > > > > > the
> > > > > > > size
> > > > > > > of
> > > > > > > the
> > > > > > > caller provided buffer as an upper limit for the read()
> > > > > > > call
> > > > > > > and
> > > > > > > not
> > > > > > > the exact amount of data to be read).
> > > > > > > Unfortunately the fs_read() semantics is fundamentally
> > > > > > > broken
> > > > > > > as
> > > > > > > it
> > > > > > > interprets 'size == 0' as 'read as much data as you can
> > > > > > > get'
> > > > > > > which
> > > > > > > may
> > > > > > > easily lead to buffer overflows and prints a very
> > > > > > > unhelpful
> > > > > > > error
> > > > > > > message "<filename> shorter than offset + len" in case
> > > > > > > 'size'
> > > > > > > does
> > > > > > > not
> > > > > > > match the actual amount of data read. 
> > > > > > > 
> > > > > > > You should also consider what happens, if the firmware
> > > > > > > file
> > > > > > > you
> > > > > > > read
> > > > > > > is
> > > > > > > larger than the buffer you provided, as in that case
> > > > > > > fs_read()
> > > > > > > will
> > > > > > > stop reading at the provided buffer size and you won't be
> > > > > > > able to
> > > > > > > notice, that the file was not completely loaded!
> > > > > > > 
> > > > > > I prefer to let the caller handles this, because this
> > > > > > function
> > > > > > can
> > > > > > be
> > > > > > used to read the firmware chunk by chunk when the allocated
> > > > > > buffer
> > > > > > is
> > > > > > smaller than firmware.
> > > > > > 
> > > > > So, the caller should also check, whether the return value of
> > > > > the
> > > > > function matches the requested size and you should omit the
> > > > > special
> > > > > handling of actread != firmware_p->size in
> > > > > fw_get_filesystem_firmware()
> > > > > (as you did in the current version of your patch).
> > > > > 
> > > > Just to confirm we are in same page, the caller i means is
> > > > function
> > > > which call the request_firmware_into_buf. firmware_p->size is
> > > > the
> > > > size
> > > > gonna be read from firmware, could be part of firmware with
> > > > different
> > > > offset.
> > > > Would you mind to explain more why the special handling should
> > > > be
> > > > omitted? This special handling would return error code if
> > > > fail,or 
> > > > actread if pass to the request_firmware_into_buf.
> > > > request_firmware_into_buf just need to know status of file
> > > > reading
> > > > is
> > > > performed successfully or not.
> > > > 
> > > The point is whether to define a short read as failure and return
> > > an
> > > error code in this case or just let the caller know the actual
> > > amount
> > > of data read. If you always return the actual number of bytes
> > > read
> > > (or
> > > a negative error code), no matter whether it matches the
> > > requested
> > > size
> > > or not, the caller has all information to handle the situation
> > > correctly. It could just request a new chunk for the missing
> > > bytes in
> > > case of a short read, or handle a short read as an error
> > > condition at
> > > its own discretion. So there is no need to check the actual read
> > > size
> > > in your function.
> > > 
> > > But probably this discussion is completely vain, since if you
> > > want to
> > > load a piece of firmware, you would probably check for the
> > > existence
> > > of the file and its size beforehand, allocate a sufficiently
> > > large
> > > buffer and then call request_firmware_into_buf() with the correct
> > > size.
> > > Thus the situation actread != size should never occur anyway in
> > > practice.
> > > 
> > Okay, so you means that regardless fs_read  is success or fail,
> > just
> > return the actread to the caller, and let caller to decide the next
> > handling action, right?
> > > 
> > > 
> NOOOOO!
> If fs_read() returns an error code, you should return that of course!
> 
> If the return code from fs_read() is zero, you should just return
> actread without spewing any message and let the caller handle the
> situation appropriately.
> 
Okay, i have no problem with that.
> 
> Lothar Waßmann