Hi Dan,
dan.carpenter@xxxxxxxxxx wrote on Thu, 19 May 2022 16:56:31 +0300:
> Hello Miquel Raynal,
>
> The patch be4a11cf98af: "rtc: rzn1: Add oscillator offset support"
> from May 16, 2022, leads to the following Smatch static checker
> warning:
>
> drivers/rtc/rtc-rzn1.c:302 rzn1_rtc_set_offset()
> warn: 'steps' 'true' implies 'steps > 0' is 'true'
>
> drivers/rtc/rtc-rzn1.c
> 270 static int rzn1_rtc_set_offset(struct device *dev, long offset)
> 271 {
> 272 struct rzn1_rtc *rtc = dev_get_drvdata(dev);
> 273 unsigned int steps;
> ^^^^^^^^^^^^^^^^^^
> steps is unsigned
>
> 274 int stepsh, stepsl;
> 275 u32 val = 0;
> 276 int ret;
> 277
> 278 /*
> 279 * Check which resolution mode (every 20 or 60s) can be used.
> 280 * Between 2 and 124 clock pulses can be added or substracted.
> 281 *
> 282 * In 20s mode, the minimum resolution is 2 / (32768 * 20) which is
> 283 * close to 3051 ppb. In 60s mode, the resolution is closer to 1017.
> 284 */
> 285 stepsh = DIV_ROUND_CLOSEST(offset, 1017);
> 286 stepsl = DIV_ROUND_CLOSEST(offset, 3051);
> 287
> 288 if (stepsh >= -0x3E && stepsh <= 0x3E) {
> 289 /* 1017 ppb per step */
> 290 steps = stepsh;
> 291 val |= RZN1_RTC_SUBU_DEV;
> 292 } else if (stepsl >= -0x3E && stepsl <= 0x3E) {
> 293 /* 3051 ppb per step */
> 294 steps = stepsl;
> 295 } else {
> 296 return -ERANGE;
> 297 }
> 298
> 299 if (!steps)
>
> if steps is zero return
>
> 300 return 0;
> 301
> --> 302 if (steps > 0) {
>
> This is true. No need to check.
'steps' should not be unsigned in order to properly carry the offset.
Do you plan to send a patch?
>
> 303 val |= steps + 1;
> 304 } else {
> 305 val |= RZN1_RTC_SUBU_DECR;
> 306 val |= (~(-steps - 1)) & 0x3F;
> 307 }
> 308
> 309 ret = readl_poll_timeout(rtc->base + RZN1_RTC_CTL2, val,
> 310 !(val & RZN1_RTC_CTL2_WUST), 100, 2000000);
> 311 if (ret)
> 312 return ret;
> 313
> 314 writel(val, rtc->base + RZN1_RTC_SUBU);
> 315
> 316 return 0;
> 317 }
>
> regards,
> dan carpenter
Thanks,
Miquèl
