Hello Takashi Iwai,

The patch 0416980d0a2b: "ALSA: line6: Fix volume calculation for big-endian" from Jan 28, 2015, leads to the following static checker warning:

sound/usb/line6/playback.c:42 change_volume() warn: always clamps to s16min sound/usb/line6/playback.c:57 change_volume() warn: always clamps to (-8388608) sound/usb/line6/playback.c:129 add_monitor_signal() warn: always clamps to s16min

sound/usb/line6/playback.c 25 static void change_volume(struct urb *urb_out, int volume[], 26 int bytes_per_frame) 27 { 28 int chn = 0; 29 30 if (volume[0] == 256 && volume[1] == 256) 31 return; /* maximum volume - no change */ 32 33 if (bytes_per_frame == 4) { 34 __le16 *p, *buf_end; 35 36 p = (__le16 *)urb_out->transfer_buffer; 37 buf_end = p + urb_out->transfer_buffer_length / sizeof(*p); 38 39 for (; p < buf_end; ++p) { 40 short pv = le16_to_cpu(*p); 41 int val = (pv * volume[chn & 1]) >> 8; 42 pv = clamp(val, 0x7fff, -0x8000); ^^^^^^^^^^^^^^^^ You didn't really add this, but you might know what was intended here. It is a complete mystery to me. :)

43 *p = cpu_to_le16(pv); 44 ++chn; 45 } 46 } else if (bytes_per_frame == 6) { 47 unsigned char *p, *buf_end; 48 49 p = (unsigned char *)urb_out->transfer_buffer; 50 buf_end = p + urb_out->transfer_buffer_length; 51 52 for (; p < buf_end; p += 3) { 53 int val; 54 55 val = p[0] + (p[1] << 8) + ((signed char)p[2] << 16); 56 val = (val * volume[chn & 1]) >> 8; 57 val = clamp(val, 0x7fffff, -0x800000); ^^^^^^^^^^^^^^^^^^^^ 58 p[0] = val; 59 p[1] = val >> 8; 60 p[2] = val >> 16; 61 ++chn; 62 } 63 } 64 }

[snip]

127 short piv = le16_to_cpu(*pi); 128 int val = pov + ((piv * volume) >> 8); 129 pov = clamp(val, 0x7fff, -0x8000); ^^^^^^^^^^^^^^^^ 130 *po = cpu_to_le16(pov); 131 }

regards, dan carpenter