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regmap: mmio: Revert to v4.4 endianness handling

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Commit 29bb45f25f (regmap-mmio: Use native endianness for read/write)
 attempted to fix some long standing bugs in the MMIO implementation for
 big endian systems caused by duplicate byte swapping in both regmap and
 readl()/writel() which affected MIPS systems as when they are in big
 endian mode they flip the endianness of all registers in the system, not
 just the CPU.  MIPS systems had worked around this by declaring regmap
 using IPs as little endian which is inaccurate, unfortunately the issue
 had not been reported.
 
 Sadly the fix makes things worse rather than better.  By changing the
 behaviour to match the documentation it caused behaviour changes for
 other IPs which broke them and by using the __raw I/O accessors to avoid
 the endianness swapping in readl()/writel() it removed some memory
 ordering guarantees and could potentially generate unvirtualisable
 instructions on some architectures.
 
 Unfortunately sorting out all this mess in any half way sensible fashion
 was far too invasive to go in during an -rc cycle so instead let's go
 back to the old broken behaviour for v4.5, the better fixes are already
 queued for v4.6.  This does mean that we keep the broken MIPS DTs for
 another release but that seems the least bad way of handling the
 situation.
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Merge tag 'regmap-fix-v4.5-big-endian' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap

Pull regmap fix from Mark Brown:
 "A single revert back to v4.4 endianness handling.

  Commit 29bb45f25f ("regmap-mmio: Use native endianness for
  read/write") attempted to fix some long standing bugs in the MMIO
  implementation for big endian systems caused by duplicate byte
  swapping in both regmap and readl()/writel().  Sadly the fix makes
  things worse rather than better, so revert it for now"

* tag 'regmap-fix-v4.5-big-endian' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: mmio: Revert to v4.4 endianness handling
This commit is contained in:
Linus Torvalds 2016-02-08 10:20:06 -08:00
commit 92e6edd685
10 changed files with 17 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/mips/boot/dts/brcm/bcm6328.dtsi
View File

@ -74,6 +74,7 @@
timer: timer@10000040 {
compatible = "syscon";
reg = <0x10000040 0x2c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7125.dtsi
View File

@ -98,6 +98,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7125-sun-top-ctrl", "syscon";
reg = <0x404000 0x60c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7346.dtsi
View File

@ -118,6 +118,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7346-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7358.dtsi
View File

@ -112,6 +112,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7358-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7360.dtsi
View File

@ -112,6 +112,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7360-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7362.dtsi
View File

@ -118,6 +118,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7362-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7420.dtsi
View File

@ -99,6 +99,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7420-sun-top-ctrl", "syscon";
reg = <0x404000 0x60c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7425.dtsi
View File

@ -100,6 +100,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7425-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
little-endian;
};
reboot {

1
arch/mips/boot/dts/brcm/bcm7435.dtsi
View File

@ -114,6 +114,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7425-sun-top-ctrl", "syscon";
reg = <0x404000 0x51c>;
little-endian;
};
reboot {

16
drivers/base/regmap/regmap-mmio.c
View File

@ -133,17 +133,17 @@ static int regmap_mmio_gather_write(void *context,
while (val_size) {
switch (ctx->val_bytes) {
case 1:
__raw_writeb(*(u8 *)val, ctx->regs + offset);
writeb(*(u8 *)val, ctx->regs + offset);
break;
case 2:
__raw_writew(*(u16 *)val, ctx->regs + offset);
writew(*(u16 *)val, ctx->regs + offset);
break;
case 4:
__raw_writel(*(u32 *)val, ctx->regs + offset);
writel(*(u32 *)val, ctx->regs + offset);
break;
#ifdef CONFIG_64BIT
case 8:
__raw_writeq(*(u64 *)val, ctx->regs + offset);
writeq(*(u64 *)val, ctx->regs + offset);
break;
#endif
default:
@ -193,17 +193,17 @@ static int regmap_mmio_read(void *context,
while (val_size) {
switch (ctx->val_bytes) {
case 1:
*(u8 *)val = __raw_readb(ctx->regs + offset);
*(u8 *)val = readb(ctx->regs + offset);
break;
case 2:
*(u16 *)val = __raw_readw(ctx->regs + offset);
*(u16 *)val = readw(ctx->regs + offset);
break;
case 4:
*(u32 *)val = __raw_readl(ctx->regs + offset);
*(u32 *)val = readl(ctx->regs + offset);
break;
#ifdef CONFIG_64BIT
case 8:
*(u64 *)val = __raw_readq(ctx->regs + offset);
*(u64 *)val = readq(ctx->regs + offset);
break;
#endif
default: