drm/mgag200: Split PLL compute function for G200SE by rev

The compute function for G200SE pixel PLLs handles two revisions with
different algorithms. Split it accordingly to make it readable. No
functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210714142240.21979-9-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_mode.c

@@ -206,102 +206,117 @@ static void mgag200_set_pixpll_g200(struct mga_device *mdev,
 	WREG_DAC(MGA1064_PIX_PLLC_P, xpixpllcp);
 }
 
-static int mgag200_compute_pixpll_values_g200se(struct mga_device *mdev, long clock,
-						struct mgag200_pll_values *pixpllc)
+static int mgag200_compute_pixpll_values_g200se_00(struct mga_device *mdev, long clock,
+						   struct mgag200_pll_values *pixpllc)
 {
-	static const unsigned int pvalues_e4[] = {16, 14, 12, 10, 8, 6, 4, 2, 1};
-
-	u32 unique_rev_id = mdev->model.g200se.unique_rev_id;
 	unsigned int vcomax, vcomin, pllreffreq;
 	unsigned int delta, tmpdelta, permitteddelta;
 	unsigned int testp, testm, testn;
 	unsigned int p, m, n, s;
 	unsigned int computed;
-	unsigned int fvv;
-	unsigned int i;
 
 	m = n = p = s = 0;
 
-	if (unique_rev_id <= 0x03) {
-		vcomax = 320000;
-		vcomin = 160000;
-		pllreffreq = 25000;
-		delta = 0xffffffff;
-		permitteddelta = clock * 5 / 1000;
+	vcomax = 320000;
+	vcomin = 160000;
+	pllreffreq = 25000;
+	permitteddelta = clock * 5 / 1000;
 
-		for (testp = 8; testp > 0; testp /= 2) {
-			if (clock * testp > vcomax)
-				continue;
-			if (clock * testp < vcomin)
-				continue;
+	for (testp = 8; testp > 0; testp /= 2) {
+		if (clock * testp > vcomax)
+			continue;
+		if (clock * testp < vcomin)
+			continue;
 
-			for (testn = 17; testn < 256; testn++) {
-				for (testm = 1; testm < 32; testm++) {
-					computed = (pllreffreq * testn) /
-						(testm * testp);
-					if (computed > clock)
-						tmpdelta = computed - clock;
-					else
-						tmpdelta = clock - computed;
-					if (tmpdelta < delta) {
-						delta = tmpdelta;
-						m = testm;
-						n = testn;
-						p = testp;
-					}
+		for (testn = 17; testn < 256; testn++) {
+			for (testm = 1; testm < 32; testm++) {
+				computed = (pllreffreq * testn) / (testm * testp);
+				if (computed > clock)
+					tmpdelta = computed - clock;
+				else
+					tmpdelta = clock - computed;
+				if (tmpdelta < delta) {
+					delta = tmpdelta;
+					m = testm;
+					n = testn;
+					p = testp;
 				}
 			}
 		}
-	} else {
-		vcomax        = 1600000;
-		vcomin        = 800000;
-		pllreffreq    = 25000;
+	}
 
-		if (clock < 25000)
-			clock = 25000;
+	if (delta > permitteddelta) {
+		pr_warn("PLL delta too large\n");
+		return -EINVAL;
+	}
 
-		clock = clock * 2;
+	pixpllc->m = m;
+	pixpllc->n = n;
+	pixpllc->p = p;
+	pixpllc->s = s;
 
-		delta = 0xFFFFFFFF;
-		/* Permited delta is 0.5% as VESA Specification */
-		permitteddelta = clock * 5 / 1000;
+	return 0;
+}
 
-		for (i = 0 ; i < ARRAY_SIZE(pvalues_e4); i++) {
-			testp = pvalues_e4[i];
+static int mgag200_compute_pixpll_values_g200se_04(struct mga_device *mdev, long clock,
+						   struct mgag200_pll_values *pixpllc)
+{
+	static const unsigned int pvalues_e4[] = {16, 14, 12, 10, 8, 6, 4, 2, 1};
 
-			if ((clock * testp) > vcomax)
-				continue;
-			if ((clock * testp) < vcomin)
-				continue;
+	unsigned int vcomax, vcomin, pllreffreq;
+	unsigned int delta, tmpdelta, permitteddelta;
+	unsigned int testp, testm, testn;
+	unsigned int p, m, n, s;
+	unsigned int computed;
+	unsigned int fvv;
+	unsigned int i;
 
-			for (testn = 50; testn <= 256; testn++) {
-				for (testm = 1; testm <= 32; testm++) {
-					computed = (pllreffreq * testn) /
-						(testm * testp);
-					if (computed > clock)
-						tmpdelta = computed - clock;
-					else
-						tmpdelta = clock - computed;
+	m = n = p = s = 0;
+	delta = 0xffffffff;
 
-					if (tmpdelta < delta) {
-						delta = tmpdelta;
-						m = testm;
-						n = testn;
-						p = testp;
-					}
+	vcomax        = 1600000;
+	vcomin        = 800000;
+	pllreffreq    = 25000;
+
+	if (clock < 25000)
+		clock = 25000;
+	clock = clock * 2;
+
+	/* Permited delta is 0.5% as VESA Specification */
+	permitteddelta = clock * 5 / 1000;
+
+	for (i = 0 ; i < ARRAY_SIZE(pvalues_e4); i++) {
+		testp = pvalues_e4[i];
+
+		if ((clock * testp) > vcomax)
+			continue;
+		if ((clock * testp) < vcomin)
+			continue;
+
+		for (testn = 50; testn <= 256; testn++) {
+			for (testm = 1; testm <= 32; testm++) {
+				computed = (pllreffreq * testn) / (testm * testp);
+				if (computed > clock)
+					tmpdelta = computed - clock;
+				else
+					tmpdelta = clock - computed;
+
+				if (tmpdelta < delta) {
+					delta = tmpdelta;
+					m = testm;
+					n = testn;
+					p = testp;
 				}
 			}
 		}
-
-		fvv = pllreffreq * n / m;
-		fvv = (fvv - 800000) / 50000;
-		if (fvv > 15)
-			fvv = 15;
-		s = fvv << 1;
-
-		clock = clock / 2;
 	}
 
+	fvv = pllreffreq * n / m;
+	fvv = (fvv - 800000) / 50000;
+	if (fvv > 15)
+		fvv = 15;
+	s = fvv << 1;
+
 	if (delta > permitteddelta) {
 		pr_warn("PLL delta too large\n");
 		return -EINVAL;
@@ -315,6 +330,17 @@ static int mgag200_compute_pixpll_values_g200se(struct mga_device *mdev, long cl
 	return 0;
 }
 
+static int mgag200_compute_pixpll_values_g200se(struct mga_device *mdev, long clock,
+						struct mgag200_pll_values *pixpllc)
+{
+	u32 unique_rev_id = mdev->model.g200se.unique_rev_id;
+
+	if (unique_rev_id >= 0x04)
+		return mgag200_compute_pixpll_values_g200se_04(mdev, clock, pixpllc);
+	else
+		return mgag200_compute_pixpll_values_g200se_00(mdev, clock, pixpllc);
+}
+
 static void mgag200_set_pixpll_g200se(struct mga_device *mdev,
 				      const struct mgag200_pll_values *pixpllc)
 {