Messages in this thread | | | Date | Tue, 19 May 2020 17:50:53 +0200 | From | Thomas Bogendoerfer <> | Subject | Re: [PATCH v2 18/20] mips: csrc-r4k: Decrease r4k-clocksource rating if CPU_FREQ enabled |
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On Mon, May 18, 2020 at 11:57:52PM +0300, Serge Semin wrote: > On Mon, May 18, 2020 at 06:32:06PM +0200, Thomas Bogendoerfer wrote: > > On Mon, May 18, 2020 at 04:48:20PM +0300, Serge Semin wrote: > > > On Fri, May 15, 2020 at 11:06:47PM +0200, Thomas Bogendoerfer wrote: > > > > On Fri, May 15, 2020 at 10:48:27AM +0300, Serge Semin wrote: > > > > > Thomas, > > > > > Could you take a look at my comment below so I could proceed with the > > > > > patchset v3 development? > > > > > > > > I can't help, but using r4k clocksource with changing frequency is > > > > probaly only usefull as a random generator. So IMHO the only two > > > > options are disabling it or implement what arch/x86/kernel/tsc.c does. > > > > > > > > Thomas. > > > > > > Thomas, could you proceed with the rest of the patches review? > > > ├─>[PATCH v2 16/20] bus: cdmm: Add MIPS R5 arch support > > > ├─>[PATCH v2 15/20] mips: cdmm: Add mti,mips-cdmm dtb node support > > > > both are not my call, but look ok to me. > > Can I add your Reviewed-by tag there then?
only for 16/20. 15/20 looks ok to me, but I have not enough insides on the hardware to say this is good.
> > > ├─>[PATCH v2 13/20] mips: early_printk_8250: Use offset-sized IO-mem accessors > > > > that's broken. A reg shift of 2 doesn't mean we could use 32bit access > > to the registers on other platforms. As I don't think adding some ifdefery > > makes things nicer, just implement the your prom_putchar in board code. > > I thought about that initially, but then I decided to alter the generic > early_printk_8250 code instead. My version of prom_putchar() would be almost > the same as one implemented in the early_printk_8250 module except minor > modification of replacing readb/writeb methods with readl/writel. So I didn't > want to duplicate the code, but wanted to provide a general way to fix the > problem potentially also for another platforms. > > Since you don't like this fix alternatively I'd suggest to add the reg_width > parameter passed to the setup_8250_early_printk_port() method like this: > -setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift, > - unsigned int timeout) > +setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift, > + unsigned int reg_width, unsigned int timeout) > > By reg_width parameter we could determine the actual width of the register: > static inline u8 serial_in(int offset) > { > - return readb(serial8250_base + (offset << serial8250_reg_shift)); > + u8 ret = 0xFF; > + > + offset <<= serial8250_reg_shift; > + switch (serial8250_reg_width) { > + case 1: > + ret = readb(serial8250_base + offset); > + break; > + case 2: > + ret = readw(serial8250_base + offset); > + break; > + case 4: > + ret = readl(serial8250_base + offset); > + break; > + default: > + break; > + } > + > + return ret; > } > > The similar modification will be implemented for serial_out(). I'll also modify
look at the lines of code you are adding. Doing your own prom_putchar will probably have less lines.
> What do you think about this?
please do your own prom_putchar.
> > > > > ├─>[PATCH v2 12/20] mips: MAAR: Add XPA mode support > > > > looks ok so far. > > Can I add your Reviewed-by tag there then?
As I'm the maintainer of the part, I've simply applied it.
> > > > > ├─>[PATCH v2 10/20] mips: Add CONFIG/CONFIG6/Cause reg fields macro > > > > that is fine > > Can I add your Reviewed-by tag there then?
As this didn't apply cleanly, I'll apply it after you've resent it. IMHO no need for a Reviewed-by.
> > > └─>[PATCH v2 09/20] mips: Add CP0 Write Merge config support > > > > this is IMHO a dangerous change. Enabling write merging for any > > CPU supporting it might triggers bugs. Do it in your board bringup > > code and at the moment I don't see a reason for the rest of that > > patch. > > Let's at least leave the mm_config() implementation but without the write-merge > enabling by default. Providing features availability macro > cpu_has_mm_sysad/cpu_has_mm_full and c0 config fields
do you have a user of that ? I'm not introducing code nobody uses.
> I could use them to implement a code pattern like: > > + if (cpu_has_mm_full) { > + unsigned int config0 = read_c0_config(); > + config0 = (config0 & ~MIPS_CONF_MM) | MIPS_CONF_MM_FULL; > + write_c0_config(config0); > + }
you know you are running on a R5 core, so you know you have MM_FULL. No need to check this.
> By doing so I can manually enable/disable the MM feature in the > cpu-feature-overrides.h. Without that I'd have to locally define these macro, > which isn't good seeing they are in fact generic and can be useful for other > platforms with SYSAD and FULL MM feature available. What do you think?
To me this is a hardware feature I expect to be done by firmware and Linux shouldn't care about it, if it doesn't have any software implications.
Thomas.
-- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]
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