Re: [PATCH 6/9] hw/display/omap_lcdc: Drop broken bigendian ifdef

[Philippe Mathieu-Daudé]

On 2/15/21 11:32 AM, Peter Maydell wrote:
> The draw_line16_32() function in the omap_lcdc template header
> includes an ifdef for the case where HOST_WORDS_BIGENDIAN matches
> TARGET_WORDS_BIGENDIAN.  This is trying to optimise for "source
> bitmap and destination bitmap format match", but it is broken,
> because in this function the formats don't match: the source is
> 16-bit colour and the destination is 32-bit colour, so a memcpy()
> will produce corrupted graphics output.  Drop the bogus ifdef.
> 
> This bug was introduced in commit ea644cf343129, when we dropped
> support for DEPTH values other than 32 from the template header.
> The old #if line was
>   #if DEPTH == 16 && defined(HOST_WORDS_BIGENDIAN) == 
> defined(TARGET_WORDS_BIGENDIAN)
> and this was mistakenly changed to
>   #if defined(HOST_WORDS_BIGENDIAN) == defined(TARGET_WORDS_BIGENDIAN)
> rather than deleting the #if as now having an always-false condition.
> 
> Fixes: ea644cf343129
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/display/omap_lcd_template.h | 4 ----
>  1 file changed, 4 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>