* Re: [PATCHv7] rtc: Add support for Intersil ISL12057 I2C RTC chip [not found] <72207bc152a06638f0e0e21a6e00d4c2054a1a71.1387489507.git.arno@natisbad.org> @ 2013-12-19 22:07 ` Andrew Morton 2013-12-19 22:22 ` Arnaud Ebalard 0 siblings, 1 reply; 2+ messages in thread From: Andrew Morton @ 2013-12-19 22:07 UTC (permalink / raw) To: Arnaud Ebalard Cc: Jason Cooper, Mark Rutland, Alessandro Zummo, Peter Huewe, Linus Walleij, Thierry Reding, Mark Brown, Guenter Roeck, Rob Herring, Pawel Moll, Stephen Warren, Ian Campbell, Grant Likely, devicetree, linux-doc, Rob Landley, rtc-linux, Jason Gunthorpe, Kumar Gala, linux-arm-kernel, linux-kernel On Thu, 19 Dec 2013 22:53:16 +0100 Arnaud Ebalard <arno@natisbad.org> wrote: > +static int isl12057_i2c_validate_chip(struct regmap *regmap) > +{ > + u8 regs[ISL12057_MEM_MAP_LEN]; > + u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8, > + 0xc0, 0x60, 0x00, 0x00, > + 0x00, 0x00, 0x00, 0x00, > + 0x00, 0x00, 0x60, 0x7c }; > + int ret, i; > + > + ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN); > + if (ret) > + return ret; > + > + for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) { > + if (regs[i] & mask[i]) /* check if bits are cleared */ > + return -ENODEV; > + } > + > + return 0; > +} When I build this for x86_64, mask[] is assembled on-stack at runtime: leaq -48(%rbp), %r14 #, tmp130 xorl %esi, %esi # movl $16, %ecx #, movq %rax, %rdi # regmap, incq .LPBX1+552(%rip) # *.LPBX1 movb $-128, -64(%rbp) #, mask movq %r14, %rdx # tmp130, movb $-128, -63(%rbp) #, mask movb $-128, -62(%rbp) #, mask movb $-8, -61(%rbp) #, mask movb $-64, -60(%rbp) #, mask movb $96, -59(%rbp) #, mask movb $0, -58(%rbp) #, mask movb $0, -57(%rbp) #, mask movb $0, -56(%rbp) #, mask movb $0, -55(%rbp) #, mask movb $0, -54(%rbp) #, mask movb $0, -53(%rbp) #, mask movb $0, -52(%rbp) #, mask movb $0, -51(%rbp) #, mask movb $96, -50(%rbp) #, mask movb $124, -49(%rbp) #, mask call regmap_bulk_read # If we make `mask' static const, that all gets done at compile time instead: leaq -48(%rbp), %r14 #, tmp134 xorl %esi, %esi # movl $16, %ecx #, movq %rax, %rdi # regmap, incq .LPBX1+552(%rip) # *.LPBX1 movq %r14, %rdx # tmp134, call regmap_bulk_read # much nicer. ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCHv7] rtc: Add support for Intersil ISL12057 I2C RTC chip 2013-12-19 22:07 ` [PATCHv7] rtc: Add support for Intersil ISL12057 I2C RTC chip Andrew Morton @ 2013-12-19 22:22 ` Arnaud Ebalard 0 siblings, 0 replies; 2+ messages in thread From: Arnaud Ebalard @ 2013-12-19 22:22 UTC (permalink / raw) To: Andrew Morton Cc: Mark Rutland, Alessandro Zummo, Jason Cooper, Pawel Moll, Stephen Warren, rtc-linux, Linus Walleij, Ian Campbell, linux-doc, linux-kernel, Rob Herring, Jason Gunthorpe, devicetree, Mark Brown, linux-arm-kernel, Rob Landley, Kumar Gala, Grant Likely, Peter Huewe, Thierry Reding, Guenter Roeck Hi Andrew, Andrew Morton <akpm@linux-foundation.org> writes: > On Thu, 19 Dec 2013 22:53:16 +0100 Arnaud Ebalard <arno@natisbad.org> wrote: > >> +static int isl12057_i2c_validate_chip(struct regmap *regmap) >> +{ >> + u8 regs[ISL12057_MEM_MAP_LEN]; >> + u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8, >> + 0xc0, 0x60, 0x00, 0x00, >> + 0x00, 0x00, 0x00, 0x00, >> + 0x00, 0x00, 0x60, 0x7c }; >> + int ret, i; >> + >> + ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN); >> + if (ret) >> + return ret; >> + >> + for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) { >> + if (regs[i] & mask[i]) /* check if bits are cleared */ >> + return -ENODEV; >> + } >> + >> + return 0; >> +} > > When I build this for x86_64, mask[] is assembled on-stack at runtime: > > leaq -48(%rbp), %r14 #, tmp130 > xorl %esi, %esi # > movl $16, %ecx #, > movq %rax, %rdi # regmap, > incq .LPBX1+552(%rip) # *.LPBX1 > movb $-128, -64(%rbp) #, mask > movq %r14, %rdx # tmp130, > movb $-128, -63(%rbp) #, mask > movb $-128, -62(%rbp) #, mask > movb $-8, -61(%rbp) #, mask > movb $-64, -60(%rbp) #, mask > movb $96, -59(%rbp) #, mask > movb $0, -58(%rbp) #, mask > movb $0, -57(%rbp) #, mask > movb $0, -56(%rbp) #, mask > movb $0, -55(%rbp) #, mask > movb $0, -54(%rbp) #, mask > movb $0, -53(%rbp) #, mask > movb $0, -52(%rbp) #, mask > movb $0, -51(%rbp) #, mask > movb $96, -50(%rbp) #, mask > movb $124, -49(%rbp) #, mask > call regmap_bulk_read # > > If we make `mask' static const, that all gets done at compile time instead: > > leaq -48(%rbp), %r14 #, tmp134 > xorl %esi, %esi # > movl $16, %ecx #, > movq %rax, %rdi # regmap, > incq .LPBX1+552(%rip) # *.LPBX1 > movq %r14, %rdx # tmp134, > call regmap_bulk_read # > > much nicer. Damned. That's a good argument for a v8 ;-) Give me some minutes to assemble one. Cheers, a+ ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2013-12-19 22:23 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <72207bc152a06638f0e0e21a6e00d4c2054a1a71.1387489507.git.arno@natisbad.org>
2013-12-19 22:07 ` [PATCHv7] rtc: Add support for Intersil ISL12057 I2C RTC chip Andrew Morton
2013-12-19 22:22 ` Arnaud Ebalard
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox
Powered by JetHome