linux-kernel - Re: [PATCH] fbdev: mx3fb: avoid warning about psABI change

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Date:   Wed, 8 Apr 2020 20:16:18 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-fbdev@...r.kernel.org, Jani Nikula <jani.nikula@...el.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Enrico Weigelt <info@...ux.net>
Subject: Re: [PATCH] fbdev: mx3fb: avoid warning about psABI change

Hi Arnd,

Thank you for the patch.

On Wed, Apr 08, 2020 at 06:25:38PM +0200, Arnd Bergmann wrote:
> The arm64 gcc-9 release warns about a change in the calling
> conventions:
> 
> drivers/video/fbdev/mx3fb.c: In function 'sdc_init_panel':
> drivers/video/fbdev/mx3fb.c:506:12: note: parameter passing for argument of type 'struct ipu_di_signal_cfg' changed in GCC 9.1
>   506 | static int sdc_init_panel(struct mx3fb_data *mx3fb, enum ipu_panel panel,
>       |            ^~~~~~~~~~~~~~
> drivers/video/fbdev/mx3fb.c: In function '__set_par':
> drivers/video/fbdev/mx3fb.c:848:7: note: parameter passing for argument of type 'struct ipu_di_signal_cfg' changed in GCC 9.1
> 
> Change the file to just pass the struct by reference, which is
> unambiguous and avoids the warning.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/video/fbdev/mx3fb.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/video/fbdev/mx3fb.c b/drivers/video/fbdev/mx3fb.c
> index 4af28e4421e5..e13fea3a292f 100644
> --- a/drivers/video/fbdev/mx3fb.c
> +++ b/drivers/video/fbdev/mx3fb.c
> @@ -509,7 +509,7 @@ static int sdc_init_panel(struct mx3fb_data *mx3fb, enum ipu_panel panel,
>  			  uint16_t h_start_width, uint16_t h_sync_width,
>  			  uint16_t h_end_width, uint16_t v_start_width,
>  			  uint16_t v_sync_width, uint16_t v_end_width,
> -			  struct ipu_di_signal_cfg sig)
> +			  struct ipu_di_signal_cfg *sig)

How about making it a const pointer ? The current code doesn't change
the contents of the caller's structure as it passes it by value, let's
ensure that stays the same. With this fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

>  {
>  	unsigned long lock_flags;
>  	uint32_t reg;
> @@ -591,17 +591,17 @@ static int sdc_init_panel(struct mx3fb_data *mx3fb, enum ipu_panel panel,
>  
>  	/* DI settings */
>  	old_conf = mx3fb_read_reg(mx3fb, DI_DISP_IF_CONF) & 0x78FFFFFF;
> -	old_conf |= sig.datamask_en << DI_D3_DATAMSK_SHIFT |
> -		sig.clksel_en << DI_D3_CLK_SEL_SHIFT |
> -		sig.clkidle_en << DI_D3_CLK_IDLE_SHIFT;
> +	old_conf |= sig->datamask_en << DI_D3_DATAMSK_SHIFT |
> +		sig->clksel_en << DI_D3_CLK_SEL_SHIFT |
> +		sig->clkidle_en << DI_D3_CLK_IDLE_SHIFT;
>  	mx3fb_write_reg(mx3fb, old_conf, DI_DISP_IF_CONF);
>  
>  	old_conf = mx3fb_read_reg(mx3fb, DI_DISP_SIG_POL) & 0xE0FFFFFF;
> -	old_conf |= sig.data_pol << DI_D3_DATA_POL_SHIFT |
> -		sig.clk_pol << DI_D3_CLK_POL_SHIFT |
> -		sig.enable_pol << DI_D3_DRDY_SHARP_POL_SHIFT |
> -		sig.Hsync_pol << DI_D3_HSYNC_POL_SHIFT |
> -		sig.Vsync_pol << DI_D3_VSYNC_POL_SHIFT;
> +	old_conf |= sig->data_pol << DI_D3_DATA_POL_SHIFT |
> +		sig->clk_pol << DI_D3_CLK_POL_SHIFT |
> +		sig->enable_pol << DI_D3_DRDY_SHARP_POL_SHIFT |
> +		sig->Hsync_pol << DI_D3_HSYNC_POL_SHIFT |
> +		sig->Vsync_pol << DI_D3_VSYNC_POL_SHIFT;
>  	mx3fb_write_reg(mx3fb, old_conf, DI_DISP_SIG_POL);
>  
>  	map = &di_mappings[mx3fb->disp_data_fmt];
> @@ -855,7 +855,7 @@ static int __set_par(struct fb_info *fbi, bool lock)
>  				   fbi->var.upper_margin,
>  				   fbi->var.vsync_len,
>  				   fbi->var.lower_margin +
> -				   fbi->var.vsync_len, sig_cfg) != 0) {
> +				   fbi->var.vsync_len, &sig_cfg) != 0) {
>  			dev_err(fbi->device,
>  				"mx3fb: Error initializing panel.\n");
>  			return -EINVAL;

-- 
Regards,

Laurent Pinchart