Hi!
I got some remarks here:
On Sat, Jun 18, 2016 at 09:17:55PM +0200, Hauke Mehrtens wrote:
> This makes it possible to open a ubi layer in device tree, this is
> helpful when the rootfs is on a ubi layer. It loops though all mtd
> partitions and mounts the partition which is compatible with
> "ubi,volume". The same was only possible with kernel command line
> arguments before.
Strictly speaking this doesn't describe what this change does.
Rather than mounting anything you are creating ubiblock devices...
More comments in-line.
>
> Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/mtd/ubi.txt | 33 ++++++++++++++
> drivers/mtd/ubi/block.c | 63 +++++++++++++++++++++++++++
> 2 files changed, 96 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/mtd/ubi.txt
>
> diff --git a/Documentation/devicetree/bindings/mtd/ubi.txt b/Documentation/devicetree/bindings/mtd/ubi.txt
> new file mode 100644
> index 0000000..5fcd47e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/ubi.txt
> @@ -0,0 +1,33 @@
> +UBI - Unsorted block images
> +
> +Describe of a UBI layer in device tree.
> +
> + - compatible: "ubi,device", This marks a partition that contains
> + a ubi layer.
> + - vid_hdr_offs: Optional parameter specifies UBI VID header position
> + to be used by UBI. (default value if 0)
> + - max_beb_per1024: Optional parameter specifies the maximum expected bad
> + eraseblock per 1024 eraseblocks.
> + (default value CONFIG_MTD_UBI_BEB_LIMIT)
> + -ubi_num: Optional parameter specifies UBI device number
> + which have to be assigned to the newly created UBI
> + device (assigned automatically by default)
> +
> +Example:
> +
> +partitions {
> + compatible = "fixed-partitions";
> + #address-cells = <1>;
> + #size-cells = <1>;
> +
> + partition@0 {
> + label = "uboot";
> + reg = <0x00000 0x100000>;
> + };
> +
> + partition@1c0000 {
> + label = "system_sw";
> + reg = <0x1c0000 0xc800000>;
> + compatible = "ubi,device";
> + };
> +};
Similar to the other patch, the example in the documentation is
swapped and doesn't match with the code added by the patch.
> diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
> index ebf46ad..5ed390d 100644
> --- a/drivers/mtd/ubi/block.c
> +++ b/drivers/mtd/ubi/block.c
Wait a moment: What about ubifs being the root filesystem? That
doesn't need a ubiblock device to be created...
> @@ -1,6 +1,7 @@
> /*
> * Copyright (c) 2014 Ezequiel Garcia
> * Copyright (c) 2011 Free Electrons
> + * Copyright (c) 2016 Hauke Mehrtens <hauke@xxxxxxxxxx>
> *
> * Driver parameter handling strongly based on drivers/mtd/ubi/build.c
> * Copyright (c) International Business Machines Corp., 2006
> @@ -41,6 +42,7 @@
> #include <linux/kernel.h>
> #include <linux/list.h>
> #include <linux/mutex.h>
> +#include <linux/of.h>
> #include <linux/slab.h>
> #include <linux/mtd/ubi.h>
> #include <linux/workqueue.h>
> @@ -628,6 +630,64 @@ static void __init ubiblock_create_from_param(void)
> }
> }
>
> +static void __init ubiblock_create_from_device_tree(void)
> +{
> + int ubi_num;
> + const char *name;
> + u32 mode;
> + struct ubi_device *ubi;
> + struct ubi_volume_desc *desc;
> + struct ubi_volume_info vi;
> + struct mtd_info *mtd;
> + struct device_node *volume;
> + int ret;
> +
> + for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++) {
> + ubi = ubi_get_device(ubi_num);
> + if (!ubi)
> + continue;
> + mtd = ubi->mtd;
> + if (!mtd || !of_device_is_compatible(mtd->dev.of_node,
> + "ubi,device")) {
> + ubi_put_device(ubi);
> + continue;
> + }
> +
> + for_each_child_of_node(mtd->dev.of_node, volume) {
> + if (!of_device_is_compatible(volume, "ubi,volume"))
> + continue;
> +
> + ret = of_property_read_string(volume, "name", &name);
> + if (ret)
> + continue;
> +
> + ret = of_property_read_u32(volume, "ubi-mode", &mode);
> + if (ret)
> + continue;
> +
> + desc = ubi_open_volume_nm(ubi_num, name, mode);
> + if (IS_ERR(desc)) {
> + pr_err(
> + "UBI: block: can't open volume %s on ubi%d, err=%ld",
> + name, ubi_num, PTR_ERR(desc));
> + continue;
> + }
> +
> + ubi_get_volume_info(desc, &vi);
> + ubi_close_volume(desc);
> +
> + ret = ubiblock_create(&vi);
> + if (ret) {
> + pr_err(
> + "UBI: block: can't add '%s' volume on ubi%d, err=%d",
> + vi.name, ubi_num, ret);
> + continue;
> + }
> + }
> + ubi_put_device(ubi);
> + }
> +}
> +
> static void ubiblock_remove_all(void)
> {
> struct ubiblock *next;
> @@ -658,6 +718,9 @@ int __init ubiblock_init(void)
> */
> ubiblock_create_from_param();
>
> + /* Attach block devices from device tree */
> + ubiblock_create_from_device_tree();
> +
Probably you also want to set ROOT_DEV similar to what we currently
do in
https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/generic/patches-4.4/493-ubi-set-ROOT_DEV-to-ubiblock-rootfs-if-unset.patch
> /*
> * Block devices are only created upon user requests, so we ignore
> * existing volumes.
> --
> 2.8.1
>
>
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