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commit c09bcc91bb94ed91f1391bffcbe294963d605732 upstream. Reading the registers without waiting for engine idle returns unpredictable values. These unpredictable values result in display corruption - if atyfb_imageblit reads the content of DP_PIX_WIDTH with the bit DP_HOST_TRIPLE_EN set (from previous invocation), the driver would never ever clear the bit, resulting in display corruption. We don't want to wait for idle because it would degrade performance, so this patch modifies the driver so that it never reads accelerator registers. HOST_CNTL doesn't have to be read, we can just write it with HOST_BYTE_ALIGN because no other part of the driver cares if HOST_BYTE_ALIGN is set. DP_PIX_WIDTH is written in the functions atyfb_copyarea and atyfb_fillrect with the default value and in atyfb_imageblit with the value set according to the source image data. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Ville Syrjälä <syrjala@sci.fi> Cc: stable@vger.kernel.org Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.