Hello Scott,
Am 17.06.2014 17:54, schrieb Scott Wood:
On Tue, 2014-06-17 at 09:15 +0200, Heiko Schocher wrote:
Following Code in drivers/mtd/nand/nand_base.c nand_do_write_ops() adapted for U-Boot:
+#ifndef __UBOOT__ /* Reject writes, which are not page aligned */ if (NOTALIGNED(to) || NOTALIGNED(ops->len)) { +else
/* Reject writes, which are not page aligned */if (NOTALIGNED(to)) {+endif
This sort of ifdeffing is a bad idea -- if a larger number of lines are ifdeffed, to avoid context conflicts, subsequent merges can silently put updates into the non-U-Boot section that are needed in the U-Boot section.
Yes, in general I agree, this is a bad idea. But I introduced it here to get all differences between U-Boot and Linux marked with the "_UBOOT_" define, so a future sync with linux should be easier ...
Plus, it impairs readability, and in this case breaks text-editor brace-matching.
Yes, could be fixed, see below.
Plus plus, that line has been that way in Linux since 2006 -- why is it being touched at all? Did you merge in changes from the previous mtd sync, or did you just copy the new files over and then try to fix resulting problems? (answered below)
Yes. Above Code is a good example. In Linux this piece of code looks like: ------------- static int nand_do_write_ops(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops) [...] ops->retlen = 0; if (!writelen) return 0;
/* Reject writes, which are not page aligned */ if (NOTALIGNED(to) || NOTALIGNED(ops->len)) { pr_notice("%s: attempt to write non page aligned data\n", __func__); return -EINVAL; }
column = to & (mtd->writesize - 1); -------------
in current U-Boot:
------------- static int nand_do_write_ops(struct mtd_info *mtd, loff_t to, struct mtd_oob_ops *ops) [...]
ops->retlen = 0; if (!writelen) return 0;
column = to & (mtd->writesize - 1); -------------
Why is this "if (NOTALIGNED(to) || NOTALIGNED(ops->len)) {" missing in U-Boot? Do we allow "not aligned writes" in U-Boot? If so, we should have documented this, and best place for it, I think, would be with a comment in the source code... so if we delete this linux code in U-Boot, mark it with the "_UBOOT_" define... and differences between linux and U-Boot are documented and visible ...
I added for U-Boot the surely good "NOTALIGNED(to)" check, but not the "NOTALIGNED(ops->len)" check, as it prevents such currently working commands: "nand write xxx yyy ${filesize}" ... Maybe this is the reason for missing this piece of linux code in U-Boot?
maybe I should add here a comment ... proposal: ------------- #ifndef __UBOOT__ /* Reject writes, which are not page aligned */ if (NOTALIGNED(to) || NOTALIGNED(ops->len)) { pr_notice("%s: attempt to write non page aligned data\n", __func__); return -EINVAL; } #else /* * Reject writes, which are not page aligned, but * in U-Boot we accept "not page aligned data len" writes * so commands for example "nand write xxx yyy ${filesize}" * are working. */ if (NOTALIGNED(to)) { pr_notice("%s: attempt to write non page aligned data\n", __func__); return -EINVAL; } #endif -------------
With this approach, the difference between linux and u-boot is documented, and text-editor brace-matching is not broken ...
as the original linux code leads in not working use of the env var "filesize". For example a "nand write 80000000 80000 ${filesize}" would not work with it ...
add CONFIG_MTD_NAND_VERIFY_WRITE from U-Boot code (only compile tested)
Documented the config defines in README
kmalloc now uses memalign for allocating memory. This prevented crashes when tested ubi/ubifs on imx6 board.
To produce this patch I did three steps:
- copied the linux source files to U-Boot tree -> commit this
- adapt license text in each file -> commit this
- make the code again compile clean and working -> commit this
OK, so you did just copy stuff over. This method will lead to U-Boot
Yes.
changes being reverted every time. You should look in the U-Boot
Yes and No. If they are documented with the "define _UBOOT_", they will pop up after the copy from linux operation and you hopefully can decide, if the U-Boot specific changes are longer necessary or not.
Above Code is a good example for that. Linux has this code since 2006, why has U-Boot not this code?
history to see what Linux version corresponded to the last mtd sync, and generate a diff relative to that.
I think, we should have the linux code as the reference, and on top of this, we should add our U-Boot changes ... Thats the reason for the git tree [1].
There we have the "simple copy from linux patch" [2]. It overwrites the U-Boot specific changes, yes, but only in an intermediate step in this git tree ... (Maybe I should add in the commit message, that this is a simple copy from linux sources)
Then a U-Boot specifc patch [3], which introduces again hopefully all U-Boot specific changes... so *all* U-Boot specific changs are documented. At last a seperate licencse file patch [4] added which changes the license text.
My hope was, that future linux mtd syncs could look like:
a) copy new linux source files to u-boot tree [1] (make a new branch go back to commit [2] ... and copy new files from linux) (commit this, to have all linux changes since last sync with linux documented) b) apply [3] and fix problems All U-Boot changes documented c) apply [4] and fix problems d) add newly added U-Boot specific patches (mark them with _UBOOT_ define if they are not yet marked with it) (maybe squash them to step b ?)
-> new git tree ready
e) squash all patches into one patch and send it to mainline ... so the mainline patch has only new changes with all U-Boot specific changes.
Thats sounds easy ... and you have all linux and all U-Boot changes visible and documented ... I must admit, I did not tried your proposal to look into the linux changes since the last mtd sync ... but that sounds the more tricky way to get this sync, as the history can be long ... and shouldn;t be the result the same?
bye, Heiko [1] http://git.denx.de/?p=u-boot/u-boot-testing.git;a=shortlog;h=refs/heads/upda... [2] http://git.denx.de/?p=u-boot/u-boot-testing.git;a=commitdiff;h=2df3d72656e13... [3] http://git.denx.de/?p=u-boot/u-boot-testing.git;a=commitdiff;h=9e571d0b0d783... [4] http://git.denx.de/?p=u-boot/u-boot-testing.git;a=commitdiff;h=65497750bfef8...