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Message-ID: <alpine.DEB.2.20.1703141012130.6742@hadrien>
Date: Tue, 14 Mar 2017 10:15:36 +0100 (CET)
From: Julia Lawall <julia.lawall@...6.fr>
To: Arushi Singhal <arushisinghal19971997@...il.com>
cc: w.d.hubbs@...il.com, chris@...-brannons.com,
outreachy-kernel@...glegroups.com, kirk@...sers.ca,
samuel.thibault@...-lyon.org, gregkh@...uxfoundation.org,
speakup@...ux-speakup.org, devel@...verdev.osuosl.org,
linux-kernel@...r.kernel.org
Subject: Re: [Outreachy kernel] [PATCH v3] staging: sm750fb: Improved code
readability
On Tue, 14 Mar 2017, Arushi Singhal wrote:
> New variables are added to make the code more readable.
>
> Signed-off-by: Arushi Singhal <arushisinghal19971997@...il.com>
> ---
> changes in v3
> - improve the patch to make code much more readable.
>
> drivers/staging/sm750fb/ddk750_mode.c | 115 ++++++++++++++++++----------------
> 1 file changed, 61 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/staging/sm750fb/ddk750_mode.c b/drivers/staging/sm750fb/ddk750_mode.c
> index 25da678179f7..150e5ed0d8ea 100644
> --- a/drivers/staging/sm750fb/ddk750_mode.c
> +++ b/drivers/staging/sm750fb/ddk750_mode.c
> @@ -81,33 +81,34 @@ static int programModeRegisters(struct _mode_parameter_t *pModeParam, struct pll
> 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 cht = CRT_HORIZONTAL_TOTAL;
> + unsigned int chttm = CRT_HORIZONTAL_TOTAL_TOTAL_MASK;
> + unsigned int phde = pModeParam->horizontal_display_end - 1;
> + unsigned int chtdem = CRT_HORIZONTAL_TOTAL_DISPLAY_END_MASK;
> +
> + poke32(cht, (((pModeParam->horizontal_total - 1) << CRT_HORIZONTAL_TOTAL_TOTAL_SHIFT) & chttm) | (phde & chtdem));
In the kernel, you should not declare new variables on the fly, within a
block. My point though was that your mapping of variables to values is
not ideal. Give names to larger chunks than just naming constants, as I
put in the example in my previous mail. There is no need to have distinct
names in each case - the names you have are distinct but not memorable
anyway. And don't create code that exceeds 80 characters.
julia
> +
> + unsigned int chs = CRT_HORIZONTAL_SYNC;
> + unsigned int chswm = CRT_HORIZONTAL_SYNC_WIDTH_MASK;
> + unsigned int phss = pModeParam->horizontal_sync_start - 1;
> + unsigned int chssm = CRT_HORIZONTAL_SYNC_START_MASK;
> +
> + poke32(chs, ((pModeParam->horizontal_sync_width << CRT_HORIZONTAL_SYNC_WIDTH_SHIFT) & chswm) | (phss & chssm));
> +
> + unsigned int cvt = CRT_VERTICAL_TOTAL;
> + unsigned int cvttm = CRT_VERTICAL_TOTAL_TOTAL_MASK;
> + unsigned int pvde = pModeParam->vertical_display_end - 1;
> + unsigned int cvtdem = CRT_VERTICAL_TOTAL_DISPLAY_END_MASK;
> +
> + poke32(cvt, (((pModeParam->vertical_total - 1) << CRT_VERTICAL_TOTAL_TOTAL_SHIFT) & cvttm) | (pvde & cvtdem));
> +
> + unsigned int cvs = CRT_VERTICAL_SYNC;
> + unsigned int cvshm = CRT_VERTICAL_SYNC_HEIGHT_MASK;
> + unsigned int pvss = pModeParam->vertical_sync_start - 1;
> + unsigned int cvssm = CRT_VERTICAL_SYNC_START_MASK;
> +
> + poke32(cvs, ((pModeParam->vertical_sync_height << CRT_VERTICAL_SYNC_HEIGHT_SHIFT) & cvshm) | (pvss & cvssm));
>
> tmp = DISPLAY_CTRL_TIMING | DISPLAY_CTRL_PLANE;
> if (pModeParam->vertical_sync_polarity)
> @@ -131,33 +132,39 @@ static int programModeRegisters(struct _mode_parameter_t *pModeParam, struct pll
>
> poke32(PANEL_PLL_CTRL, sm750_format_pll_reg(pll));
>
> - reg = ((pModeParam->horizontal_total - 1) <<
> - PANEL_HORIZONTAL_TOTAL_TOTAL_SHIFT) &
> - PANEL_HORIZONTAL_TOTAL_TOTAL_MASK;
> - reg |= ((pModeParam->horizontal_display_end - 1) &
> - PANEL_HORIZONTAL_TOTAL_DISPLAY_END_MASK);
> - poke32(PANEL_HORIZONTAL_TOTAL, reg);
> -
> - poke32(PANEL_HORIZONTAL_SYNC,
> - ((pModeParam->horizontal_sync_width <<
> - PANEL_HORIZONTAL_SYNC_WIDTH_SHIFT) &
> - PANEL_HORIZONTAL_SYNC_WIDTH_MASK) |
> - ((pModeParam->horizontal_sync_start - 1) &
> - PANEL_HORIZONTAL_SYNC_START_MASK));
> -
> - poke32(PANEL_VERTICAL_TOTAL,
> - (((pModeParam->vertical_total - 1) <<
> - PANEL_VERTICAL_TOTAL_TOTAL_SHIFT) &
> - PANEL_VERTICAL_TOTAL_TOTAL_MASK) |
> - ((pModeParam->vertical_display_end - 1) &
> - PANEL_VERTICAL_TOTAL_DISPLAY_END_MASK));
> -
> - poke32(PANEL_VERTICAL_SYNC,
> - ((pModeParam->vertical_sync_height <<
> - PANEL_VERTICAL_SYNC_HEIGHT_SHIFT) &
> - PANEL_VERTICAL_SYNC_HEIGHT_MASK) |
> - ((pModeParam->vertical_sync_start - 1) &
> - PANEL_VERTICAL_SYNC_START_MASK));
> + unsigned int phttm = PANEL_HORIZONTAL_TOTAL_TOTAL_MASK;
> +
> + reg = ((pModeParam->horizontal_total - 1) << PANEL_HORIZONTAL_TOTAL_TOTAL_SHIFT) & phttm;
> +
> + unsigned int phde = pModeParam->horizontal_display_end - 1;
> + unsigned int phtdem = PANEL_HORIZONTAL_TOTAL_DISPLAY_END_MASK;
> +
> + reg |= (phde & phtdem);
> +
> + unsigned int pht = PANEL_HORIZONTAL_TOTAL;
> +
> + poke32(pht, reg);
> +
> + unsigned int phs = PANEL_HORIZONTAL_SYNC;
> + unsigned int phswm = PANEL_HORIZONTAL_SYNC_WIDTH_MASK;
> + unsigned int phss = pModeParam->horizontal_sync_start - 1;
> + unsigned int phssm = PANEL_HORIZONTAL_SYNC_START_MASK;
> +
> + poke32(phs, ((pModeParam->horizontal_sync_width << PANEL_HORIZONTAL_SYNC_WIDTH_SHIFT) & phswm) | (phss & phssm));
> +
> + unsigned int pvt = PANEL_VERTICAL_TOTAL;
> + unsigned int pvttm = PANEL_VERTICAL_TOTAL_TOTAL_MASK;
> + unsigned int pvde = pModeParam->vertical_display_end - 1;
> + unsigned int pvtdem = PANEL_VERTICAL_TOTAL_DISPLAY_END_MASK;
> +
> + poke32(pvt, (((pModeParam->vertical_total - 1) << PANEL_VERTICAL_TOTAL_TOTAL_SHIFT) & pvttm) | (pvde & pvtdem));
> +
> + unsigned int pvs = PANEL_VERTICAL_SYNC;
> + unsigned int pvshm = PANEL_VERTICAL_SYNC_HEIGHT_MASK;
> + unsigned int pvss = pModeParam->vertical_sync_start - 1;
> + unsigned int pvssm = PANEL_VERTICAL_SYNC_START_MASK;
> +
> + poke32(pvs, ((pModeParam->vertical_sync_height << PANEL_VERTICAL_SYNC_HEIGHT_SHIFT) & pvshm) | (pvss & pvssm));
>
> tmp = DISPLAY_CTRL_TIMING | DISPLAY_CTRL_PLANE;
> if (pModeParam->vertical_sync_polarity)
> --
> 2.11.0
>
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