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SubjectRe: [PATCH] media: dvb-frontends: add Socionext SC1501A ISDB-S/T demodulator driver
Hi Katsuhiro,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linuxtv-media/master]
[also build test WARNING on v4.17-rc5 next-20180514]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Katsuhiro-Suzuki/media-dvb-frontends-add-Socionext-SC1501A-ISDB-S-T-demodulator-driver/20180515-091453
base: git://linuxtv.org/media_tree.git master
reproduce:
# apt-get install sparse
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

>> drivers/media/dvb-frontends/sc1501a.c:313:47: sparse: constant 211243671486 is so big it is long

vim +313 drivers/media/dvb-frontends/sc1501a.c

258
259 static int sc1501a_s_read_status(struct sc1501a_priv *chip,
260 struct dtv_frontend_properties *c,
261 enum fe_status *status)
262 {
263 struct regmap *r_s = chip->regmap_s;
264 u32 cpmon, tmpu, tmpl, flg;
265 u64 tmp;
266
267 /* Sync detection */
268 regmap_read(r_s, CPMON1_S, &cpmon);
269
270 *status = 0;
271 if (cpmon & CPMON1_S_FSYNC)
272 *status |= FE_HAS_VITERBI | FE_HAS_SYNC | FE_HAS_LOCK;
273 if (cpmon & CPMON1_S_W2LOCK)
274 *status |= FE_HAS_SIGNAL | FE_HAS_CARRIER;
275
276 /* Signal strength */
277 c->strength.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
278
279 if (*status & FE_HAS_SIGNAL) {
280 u32 agc;
281
282 regmap_read(r_s, AGCREAD_S, &tmpu);
283 agc = tmpu << 8;
284
285 c->strength.len = 1;
286 c->strength.stat[0].scale = FE_SCALE_RELATIVE;
287 c->strength.stat[0].uvalue = agc;
288 }
289
290 /* C/N rate */
291 c->cnr.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
292
293 if (*status & FE_HAS_VITERBI) {
294 u32 cnr = 0, x, y, d;
295 u64 d_3 = 0;
296
297 regmap_read(r_s, CNRDXU_S, &tmpu);
298 regmap_read(r_s, CNRDXL_S, &tmpl);
299 x = (tmpu << 8) | tmpl;
300 regmap_read(r_s, CNRDYU_S, &tmpu);
301 regmap_read(r_s, CNRDYL_S, &tmpl);
302 y = (tmpu << 8) | tmpl;
303
304 /* CNR[dB]: 10 * log10(D) - 30.74 / D^3 - 3 */
305 /* D = x^2 / (2^15 * y - x^2) */
306 d = (y << 15) - x * x;
307 if (d > 0) {
308 /* (2^4 * D)^3 = 2^12 * D^3 */
309 /* 3.074 * 2^(12 + 24) = 211243671486 */
310 d_3 = div_u64(16 * x * x, d);
311 d_3 = d_3 * d_3 * d_3;
312 if (d_3)
> 313 d_3 = div_u64(211243671486, d_3);
314 }
315
316 if (d_3) {
317 /* 0.3 * 2^24 = 5033164 */
318 tmp = (s64)2 * intlog10(x) - intlog10(abs(d)) - d_3
319 - 5033164;
320 cnr = div_u64(tmp * 10000, 1 << 24);
321 }
322
323 if (cnr) {
324 c->cnr.len = 1;
325 c->cnr.stat[0].scale = FE_SCALE_DECIBEL;
326 c->cnr.stat[0].uvalue = cnr;
327 }
328 }
329
330 /* BER */
331 c->post_bit_error.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
332 c->post_bit_count.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
333
334 regmap_read(r_s, BERCNFLG_S, &flg);
335
336 if ((*status & FE_HAS_VITERBI) && (flg & BERCNFLG_S_BERVRDY)) {
337 u32 bit_err, bit_cnt;
338
339 regmap_read(r_s, BERVRDU_S, &tmpu);
340 regmap_read(r_s, BERVRDL_S, &tmpl);
341 bit_err = (tmpu << 8) | tmpl;
342 bit_cnt = (1 << 13) * 204;
343
344 if (bit_cnt) {
345 c->post_bit_error.len = 1;
346 c->post_bit_error.stat[0].scale = FE_SCALE_COUNTER;
347 c->post_bit_error.stat[0].uvalue = bit_err;
348 c->post_bit_count.len = 1;
349 c->post_bit_count.stat[0].scale = FE_SCALE_COUNTER;
350 c->post_bit_count.stat[0].uvalue = bit_cnt;
351 }
352 }
353
354 return 0;
355 }
356

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

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