On Sun, Jun 19, 2016 at 11:36:19PM +0200, Hauke Mehrtens wrote:
> On 06/19/2016 01:56 AM, Daniel Golle wrote:
> > 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...
>
> Should I write an error message and do nothing when this is a ubifs
> partition?
Just do nothing if you find a UBIFS magic. I reckon there shouldn't
be any error message because it's not an error but rather just another
valid case. Maybe an info message could be useful for starters...
>
> >> @@ -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
> >>
> >>
> >> ______________________________________________________
> >> Linux MTD discussion mailing list
> >> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>
>
> ______________________________________________________
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> http://lists.infradead.org/mailman/listinfo/linux-mtd/
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