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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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On Sun Ultra 5, it happens that the dot clock is not set up properly for some videomodes. For example, if we set the videomode "r1024x768x60" in the firmware, Linux would incorrectly set a videomode with refresh rate 180Hz when booting (suprisingly, my LCD monitor can display it, although display quality is very low). The reason is this: Older mach64 cards set the divider in the register VCLK_POST_DIV. The register has four 2-bit fields (the field that is actually used is specified in the lowest two bits of the register CLOCK_CNTL). The 2 bits select divider "1, 2, 4, 8". On newer mach64 cards, there's another bit added - the top four bits of PLL_EXT_CNTL extend the divider selection, so we have possible dividers "1, 2, 4, 8, 3, 5, 6, 12". The Linux driver clears the top four bits of PLL_EXT_CNTL and never sets them, so it can work regardless if the card supports them. However, the sparc64 firmware may set these extended dividers during boot - and the mach64 driver detects incorrect dot clock in this case. This patch makes the driver read the additional divider bit from PLL_EXT_CNTL and calculate the initial refresh rate properly. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Acked-by: David S. Miller <davem@davemloft.net> Reviewed-by: Ville Syrjälä <syrjala@sci.fi> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| .. | ||
| backlight | ||
| console | ||
| fbdev | ||
| logo | ||
| display_timing.c | ||
| hdmi.c | ||
| Kconfig | ||
| Makefile | ||
| of_display_timing.c | ||
| of_videomode.c | ||
| vgastate.c | ||
| videomode.c | ||