On Thu, Jul 14, 2022 at 11:33 PM Joe Perches <joe@xxxxxxxxxxx> wrote: > > On Mon, 2022-07-11 at 14:29 -0700, Justin Stitt wrote: > > When building with Clang we encounter this warning: > > > drivers/net/wireless/mediatek/mt7601u/debugfs.c:92:6: error: format > > > specifies type 'unsigned char' but the argument has type 'int' > > > [-Werror,-Wformat] dev->ee->reg.start + dev->ee->reg.num - 1); > > > > The format specifier used is `%hhu` which describes a u8. Both > > `dev->ee->reg.start` and `.num` are u8 as well. However, the expression > > as a whole is promoted to an int as you cannot get smaller-than-int from > > addition. Therefore, to fix the warning, use the promoted-to-type's > > format specifier -- in this case `%d`. > > I think whenever a sizeof(unsigned type) that is less than sizeof(int) is > emitted with vsprintf, the preferred format specifier should be %u not %d. I believe the standard recommends using the promoted-to-type's format specifier, in this case integer. I agree, though, that it is quite bizarre to represent unsigned types with signed types. I'd be interested in hearing more opinions on the matter. > > diff --git a/drivers/net/wireless/mediatek/mt7601u/debugfs.c b/drivers/net/wireless/mediatek/mt7601u/debugfs.c > [] > > @@ -88,7 +88,7 @@ mt7601u_eeprom_param_show(struct seq_file *file, void *data) > > dev->ee->rssi_offset[0], dev->ee->rssi_offset[1]); > > seq_printf(file, "Reference temp: %hhx\n", dev->ee->ref_temp); > > seq_printf(file, "LNA gain: %hhx\n", dev->ee->lna_gain); > > - seq_printf(file, "Reg channels: %hhu-%hhu\n", dev->ee->reg.start, > > + seq_printf(file, "Reg channels: %hhu-%d\n", dev->ee->reg.start, > > dev->ee->reg.start + dev->ee->reg.num - 1); > > And this is not a promotion of an argument to int via varargs. > The arithmetic did the promotion. Right, I noted in my patch message that the type promotion was due to addition. > > I suggest s/%hh/%/ for all the uses here, not just this one. I also contemplated this change but I think it might be a bit out of scope for https://github.com/ClangBuiltLinux/linux/issues/378 -- What do you think? It could be argued that every single instance of %hh[dux] should be replaced with %[dux]. > checkpatch could do this somewhat automatically. > Of course any changes it suggests need human review. > > $ ./scripts/checkpatch.pl -f drivers/net/wireless/mediatek/mt7601u/debugfs.c --show-types --types=unnecessary_modifier --fix-inplace > $ git diff --stat -p drivers/net/wireless/mediatek/mt7601u/debugfs.c > --- > drivers/net/wireless/mediatek/mt7601u/debugfs.c | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) > > diff --git a/drivers/net/wireless/mediatek/mt7601u/debugfs.c b/drivers/net/wireless/mediatek/mt7601u/debugfs.c > index 20669eacb66ea..b7a6376e3352e 100644 > --- a/drivers/net/wireless/mediatek/mt7601u/debugfs.c > +++ b/drivers/net/wireless/mediatek/mt7601u/debugfs.c > @@ -83,28 +83,28 @@ mt7601u_eeprom_param_show(struct seq_file *file, void *data) > struct tssi_data *td = &dev->ee->tssi_data; > int i; > > - seq_printf(file, "RF freq offset: %hhx\n", dev->ee->rf_freq_off); > - seq_printf(file, "RSSI offset: %hhx %hhx\n", > + seq_printf(file, "RF freq offset: %x\n", dev->ee->rf_freq_off); > + seq_printf(file, "RSSI offset: %x %x\n", > dev->ee->rssi_offset[0], dev->ee->rssi_offset[1]); > - seq_printf(file, "Reference temp: %hhx\n", dev->ee->ref_temp); > - seq_printf(file, "LNA gain: %hhx\n", dev->ee->lna_gain); > - seq_printf(file, "Reg channels: %hhu-%hhu\n", dev->ee->reg.start, > + seq_printf(file, "Reference temp: %x\n", dev->ee->ref_temp); > + seq_printf(file, "LNA gain: %x\n", dev->ee->lna_gain); > + seq_printf(file, "Reg channels: %u-%u\n", dev->ee->reg.start, > dev->ee->reg.start + dev->ee->reg.num - 1); > > seq_puts(file, "Per rate power:\n"); > for (i = 0; i < 2; i++) > - seq_printf(file, "\t raw:%02hhx bw20:%02hhx bw40:%02hhx\n", > + seq_printf(file, "\t raw:%02x bw20:%02x bw40:%02x\n", > rp->cck[i].raw, rp->cck[i].bw20, rp->cck[i].bw40); > for (i = 0; i < 4; i++) > - seq_printf(file, "\t raw:%02hhx bw20:%02hhx bw40:%02hhx\n", > + seq_printf(file, "\t raw:%02x bw20:%02x bw40:%02x\n", > rp->ofdm[i].raw, rp->ofdm[i].bw20, rp->ofdm[i].bw40); > for (i = 0; i < 4; i++) > - seq_printf(file, "\t raw:%02hhx bw20:%02hhx bw40:%02hhx\n", > + seq_printf(file, "\t raw:%02x bw20:%02x bw40:%02x\n", > rp->ht[i].raw, rp->ht[i].bw20, rp->ht[i].bw40); > > seq_puts(file, "Per channel power:\n"); > for (i = 0; i < 7; i++) > - seq_printf(file, "\t tx_power ch%u:%02hhx ch%u:%02hhx\n", > + seq_printf(file, "\t tx_power ch%u:%02x ch%u:%02x\n", > i * 2 + 1, dev->ee->chan_pwr[i * 2], > i * 2 + 2, dev->ee->chan_pwr[i * 2 + 1]); > > @@ -112,8 +112,8 @@ mt7601u_eeprom_param_show(struct seq_file *file, void *data) > return 0; > > seq_puts(file, "TSSI:\n"); > - seq_printf(file, "\t slope:%02hhx\n", td->slope); > - seq_printf(file, "\t offset=%02hhx %02hhx %02hhx\n", > + seq_printf(file, "\t slope:%02x\n", td->slope); > + seq_printf(file, "\t offset=%02x %02x %02x\n", > td->offset[0], td->offset[1], td->offset[2]); > seq_printf(file, "\t delta_off:%08x\n", td->tx0_delta_offset); > >
