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Message-ID: <YdmPho2GpVcvWUgU@errol.ini.cmu.edu>
Date: Sat, 8 Jan 2022 08:20:06 -0500
From: "Gabriel L. Somlo" <gsomlo@...il.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"kgugala@...micro.com" <kgugala@...micro.com>,
"mholenko@...micro.com" <mholenko@...micro.com>,
"krakoczy@...micro.com" <krakoczy@...micro.com>,
"mdudek@...ernships.antmicro.com" <mdudek@...ernships.antmicro.com>,
"paulus@...abs.org" <paulus@...abs.org>,
"joel@....id.au" <joel@....id.au>,
"shorne@...il.com" <shorne@...il.com>,
"geert@...ux-m68k.org" <geert@...ux-m68k.org>,
"david.abdurachmanov@...ive.com" <david.abdurachmanov@...ive.com>,
"florent@...oy-digital.fr" <florent@...oy-digital.fr>,
"rdunlap@...radead.org" <rdunlap@...radead.org>
Subject: Re: [PATCH v8 3/3] mmc: Add driver for LiteX's LiteSDCard interface
On Sat, Jan 08, 2022 at 01:26:08PM +0200, Andy Shevchenko wrote:
> On Sat, Jan 8, 2022 at 3:57 AM Gabriel L. Somlo <gsomlo@...il.com> wrote:
> > On Sat, Jan 08, 2022 at 01:54:07AM +0200, Andy Shevchenko wrote:
> > > On Saturday, January 8, 2022, Gabriel Somlo <gsomlo@...il.com> wrote:
>
> > > + u32 div;
> > > +
> > > + div = freq ? host->ref_clk / freq : 256U;
> > >
> > > + div = roundup_pow_of_two(div);
> > > + div = clamp(div, 2U, 256U);
> > >
> > > Logically seems to me that you may join these two together, because clamped
> > > range is power-of-2 one.
> >
> > `div` needs to be a power-of-2 when written to the LITEX_PHY_CLOCKERDIV
> > register (below). And clamp() will just enforce a min/max range, so if
> > (div = ref_clk / freq) ends up e.g., 5, I need both roundup_pow_of_two()
> > to bump it to 8, and clamp() to enforce that it's between 2 and 256.
> >
> > Unless you mean I should simply write it like:
> >
> > div = clamp(roundup_pow_of_two(div), 2U, 256U);
> >
> > ... as a single line?
>
> Yes, that's what I meant.
Turns out, clamp really hates being passed roundup_pow_of_two()
directly (see below). I think it's probably better if we leave
them as-is, to avoid going the explicit cast route which Geert
recommended against.
I'll send out v9 later today with everything else, including
devm_add_action_or_reset().
Thanks,
--Gabriel
drivers/mmc/host/litex_mmc.c: In function 'litex_mmc_setclk':
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:52:25: note: in expansion of macro '__careful_cmp'
52 | #define max(x, y) __careful_cmp(x, y, >)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:45: note: in expansion of macro 'max'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
In file included from ./include/linux/bits.h:5,
from drivers/mmc/host/litex_mmc.c:12:
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/const.h:12:55: note: in definition of macro '__is_constexpr'
12 | (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
| ^
./include/linux/minmax.h:26:39: note: in expansion of macro '__no_side_effects'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:52:25: note: in expansion of macro '__careful_cmp'
52 | #define max(x, y) __careful_cmp(x, y, >)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:45: note: in expansion of macro 'max'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
In file included from ./include/linux/kernel.h:17,
from ./include/linux/clk.h:13,
from drivers/mmc/host/litex_mmc.c:13:
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/minmax.h:28:27: note: in definition of macro '__cmp'
28 | #define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
| ^
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:52:25: note: in expansion of macro '__careful_cmp'
52 | #define max(x, y) __careful_cmp(x, y, >)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:45: note: in expansion of macro 'max'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/minmax.h:28:40: note: in definition of macro '__cmp'
28 | #define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
| ^
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:52:25: note: in expansion of macro '__careful_cmp'
52 | #define max(x, y) __careful_cmp(x, y, >)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:45: note: in expansion of macro 'max'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/minmax.h:31:24: note: in definition of macro '__cmp_once'
31 | typeof(x) unique_x = (x); \
| ^
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:52:25: note: in expansion of macro '__careful_cmp'
52 | #define max(x, y) __careful_cmp(x, y, >)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:45: note: in expansion of macro 'max'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
./include/linux/minmax.h:20:35: warning: comparison of distinct pointer types lacks a cast
20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
| ^~
./include/linux/minmax.h:31:39: note: in definition of macro '__cmp_once'
31 | typeof(x) unique_x = (x); \
| ^
./include/linux/minmax.h:45:25: note: in expansion of macro '__careful_cmp'
45 | #define min(x, y) __careful_cmp(x, y, <)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:28: note: in expansion of macro 'min'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
./include/linux/minmax.h:26:18: note: in expansion of macro '__typecheck'
26 | (__typecheck(x, y) && __no_side_effects(x, y))
| ^~~~~~~~~~~
./include/linux/minmax.h:36:31: note: in expansion of macro '__safe_cmp'
36 | __builtin_choose_expr(__safe_cmp(x, y), \
| ^~~~~~~~~~
./include/linux/minmax.h:52:25: note: in expansion of macro '__careful_cmp'
52 | #define max(x, y) __careful_cmp(x, y, >)
| ^~~~~~~~~~~~~
./include/linux/minmax.h:89:45: note: in expansion of macro 'max'
89 | #define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
| ^~~
drivers/mmc/host/litex_mmc.c:448:15: note: in expansion of macro 'clamp'
448 | div = clamp(roundup_pow_of_two(div), 2U, 256U);
| ^~~~~
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