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drm/ast: Don't assume DVO enabled means SIL164 on uninitialized chips

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It looks like the AST2400 comes up with the DVO enable bit set,
which causes us to incorrectly assume we have a SIL164 regardless
of the value of the scratch registers setup by the BMC firmware.

So let's limit that test to the case where the chip has already
been setup by a BIOS.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Benjamin Herrenschmidt 2014-09-04 17:50:21 +10:00 committed by Dave Airlie
parent 261a3ad426
commit 42fb142744
1 changed files with 10 additions and 4 deletions
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14
drivers/gpu/drm/ast/ast_main.c
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@ -158,16 +158,22 @@ static int ast_detect_chip(struct drm_device *dev, bool *need_post)
/*
* VGACRA3 Enhanced Color Mode Register, check if DVO is already
* enabled, in that case, assume we have a SIL164 TMDS transmitter
*
* Don't make that assumption if we the chip wasn't enabled and
* is at power-on reset, otherwise we'll incorrectly "detect" a
* SIL164 when there is none.
*/
jreg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xa3, 0xff);
if (jreg & 0x80)
ast->tx_chip_type = AST_TX_SIL164;
if (!*need_post) {
jreg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xa3, 0xff);
if (jreg & 0x80)
ast->tx_chip_type = AST_TX_SIL164;
}
if ((ast->chip == AST2300) || (ast->chip == AST2400)) {
/*
* On AST2300 and 2400, look the configuration set by the SoC in
* the SOC scratch register #1 bits 11:8 (interestingly marked
* as "reserved" in the spec
* as "reserved" in the spec)
*/
jreg = ast_get_index_reg_mask(ast, AST_IO_CRTC_PORT, 0xd1, 0xff);
switch (jreg) {