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

On Sun, Mar 19, 2017 at 4:52 PM, Arushi Singhal
[off-list ref] wrote:

On Sun, Mar 19, 2017 at 7:34 PM, Geert Uytterhoeven [off-list ref]
wrote:

quoted

On Sun, Mar 19, 2017 at 2:11 PM, Julia Lawall [off-list ref]
wrote:

quoted

On Sun, 19 Mar 2017, Arushi Singhal wrote:

quoted

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.

Arushi: have you tried to compile this?

Yes.
It's not showing any error.

No, not an error.

Is it not fine when you compiled :( ?

 But you did introduce warnings, like:

drivers/staging/sm750fb/ddk750_mode.c: In function 'programModeRegisters':
drivers/staging/sm750fb/ddk750_mode.c:87:3: warning: ISO C90 forbids
mixed declarations and code [-Wdeclaration-after-statement]

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds