Thread (3 messages) 3 messages, 3 authors, 2017-03-19

Re: [Outreachy kernel] [PATCH v3] staging: sm750fb: Code readability is improved

From: Julia Lawall <hidden>
Date: 2017-03-19 13:14:12
Also in: lkml


On Sun, 19 Mar 2017, Arushi Singhal wrote:
quoted hunk ↗ jump to hunk
New variables are added to make the code more readable.

Signed-off-by: Arushi Singhal <redacted>
---
 changes in v3
 -try to make the code much more readable.

 drivers/staging/sm750fb/ddk750_mode.c | 61 ++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 26 deletions(-)
diff --git a/drivers/staging/sm750fb/ddk750_mode.c b/drivers/staging/sm750fb/ddk750_mode.c
index eea5aef2956f..5f18ce4d10de 100644
--- a/drivers/staging/sm750fb/ddk750_mode.c
+++ b/drivers/staging/sm750fb/ddk750_mode.c
@@ -81,33 +81,42 @@ static int programModeRegisters(mode_parameter_t *pModeParam, struct pll_value *
 	if (pll->clockType = SECONDARY_PLL) {
 		/* programe secondary pixel clock */
 		poke32(CRT_PLL_CTRL, sm750_format_pll_reg(pll));
-		poke32(CRT_HORIZONTAL_TOTAL,
-		       (((pModeParam->horizontal_total - 1) <<
-			 CRT_HORIZONTAL_TOTAL_TOTAL_SHIFT) &
-			CRT_HORIZONTAL_TOTAL_TOTAL_MASK) |
-		       ((pModeParam->horizontal_display_end - 1) &
-			CRT_HORIZONTAL_TOTAL_DISPLAY_END_MASK));
-
-		poke32(CRT_HORIZONTAL_SYNC,
-		       ((pModeParam->horizontal_sync_width <<
-			 CRT_HORIZONTAL_SYNC_WIDTH_SHIFT) &
-			CRT_HORIZONTAL_SYNC_WIDTH_MASK) |
-		       ((pModeParam->horizontal_sync_start - 1) &
-			CRT_HORIZONTAL_SYNC_START_MASK));

-		poke32(CRT_VERTICAL_TOTAL,
-		       (((pModeParam->vertical_total - 1) <<
-			 CRT_VERTICAL_TOTAL_TOTAL_SHIFT) &
-			CRT_VERTICAL_TOTAL_TOTAL_MASK) |
-		       ((pModeParam->vertical_display_end - 1) &
-			CRT_VERTICAL_TOTAL_DISPLAY_END_MASK));
-
-		poke32(CRT_VERTICAL_SYNC,
-		       ((pModeParam->vertical_sync_height <<
-			 CRT_VERTICAL_SYNC_HEIGHT_SHIFT) &
-			CRT_VERTICAL_SYNC_HEIGHT_MASK) |
-		       ((pModeParam->vertical_sync_start - 1) &
-			CRT_VERTICAL_SYNC_START_MASK));
+		unsigned int a = (pModeParam->horizontal_total - 1) <<
+				CRT_HORIZONTAL_TOTAL_TOTAL_SHIFT;
+		unsigned int b = a & CRT_HORIZONTAL_TOTAL_TOTAL_MASK;
+		unsigned int c = (pModeParam->horizontal_display_end - 1) &
+				CRT_HORIZONTAL_TOTAL_DISPLAY_END_MASK;
+		unsigned int temp = b | c;
+
+		poke32(CRT_HORIZONTAL_TOTAL, temp);
+
+		unsigned int a = (pModeParam->horizontal_sync_width <<
+				CRT_HORIZONTAL_SYNC_WIDTH_SHIFT);
+		unsigned int b = a & CRT_HORIZONTAL_SYNC_WIDTH_MASK;
+		unsigned int c = (pModeParam->horizontal_sync_start - 1) &
+				CRT_HORIZONTAL_SYNC_START_MASK;
+		unsigned int temp = b | c;
This is back to the original incorrect solution.  You can't declare
variables on the fly in Linux code.  Variables have to be declared at the
top of a block.

But you can reuse the same variables over and over, if no one cares about
their previous values.

julia

+
+		poke32(CRT_HORIZONTAL_SYNC, temp);
+
+		unsigned int a = (pModeParam->vertical_total - 1) <<
+				CRT_VERTICAL_TOTAL_TOTAL_SHIFT;
+		unsigned int b = a & CRT_VERTICAL_TOTAL_TOTAL_MASK;
+		unsigned int c = (pModeParam->vertical_display_end - 1) &
+				CRT_VERTICAL_TOTAL_DISPLAY_END_MASK;
+		unsigned int temp = b | c;
+
+		poke32(CRT_VERTICAL_TOTAL, temp);
+
+		unsigned int a = pModeParam->vertical_sync_height <<
+				CRT_VERTICAL_SYNC_HEIGHT_SHIFT;
+		unsigned int b = a & CRT_VERTICAL_SYNC_HEIGHT_MASK;
+		unsigned int c = (pModeParam->vertical_sync_start - 1) &
+				CRT_VERTICAL_SYNC_START_MASK;
+		unsigned int temp = b | c;
+
+		poke32(CRT_VERTICAL_SYNC, temp);

 		tmp = DISPLAY_CTRL_TIMING | DISPLAY_CTRL_PLANE;
 		if (pModeParam->vertical_sync_polarity)
--
2.11.0

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