minmax: reduce min/max macro expansion in atomisp driver

Avoid unnecessary nested min()/max() which results in egregious macro
expansion.

Use clamp_t() as this introduces the least possible expansion, and turn
the {s,u}DIGIT_FITTING() macros into inline functions to avoid the
nested expansion.

This resolves an issue with slackware 15.0 32-bit compilation as
reported by Richard Narron.

Presumably the min/max fixups would be difficult to backport, this patch
should be easier and fix's Richard's problem in 5.15.

Reported-by: Richard Narron <[email protected]>
Reviewed-by: Hans de Goede <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Fixes: 867046c ("minmax: relax check to allow comparison between unsigned arguments and signed constants")
Cc: [email protected]
Signed-off-by: Lorenzo Stoakes <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: lorenzo-stoakes

drivers/staging/media/atomisp/pci/sh_css_frac.h

@@ -32,12 +32,24 @@
 #define uISP_VAL_MAX		      ((unsigned int)((1 << uISP_REG_BIT) - 1))
 
 /* a:fraction bits for 16bit precision, b:fraction bits for ISP precision */
-#define sDIGIT_FITTING(v, a, b) \
-	min_t(int, max_t(int, (((v) >> sSHIFT) >> max(sFRACTION_BITS_FITTING(a) - (b), 0)), \
-	  sISP_VAL_MIN), sISP_VAL_MAX)
-#define uDIGIT_FITTING(v, a, b) \
-	min((unsigned int)max((unsigned)(((v) >> uSHIFT) \
-	>> max((int)(uFRACTION_BITS_FITTING(a) - (b)), 0)), \
-	  uISP_VAL_MIN), uISP_VAL_MAX)
+static inline int sDIGIT_FITTING(int v, int a, int b)
+{
+	int fit_shift = sFRACTION_BITS_FITTING(a) - b;
+
+	v >>= sSHIFT;
+	v >>= fit_shift > 0 ? fit_shift : 0;
+
+	return clamp_t(int, v, sISP_VAL_MIN, sISP_VAL_MAX);
+}
+
+static inline unsigned int uDIGIT_FITTING(unsigned int v, int a, int b)
+{
+	int fit_shift = uFRACTION_BITS_FITTING(a) - b;
+
+	v >>= uSHIFT;
+	v >>= fit_shift > 0 ? fit_shift : 0;
+
+	return clamp_t(unsigned int, v, uISP_VAL_MIN, uISP_VAL_MAX);
+}
 
 #endif /* __SH_CSS_FRAC_H */