drm/msm/dsi: Use a better way to figure out DSI version

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The current version checking mechanism works fine for DSI6G blocks. It
doesn't work so well for older generation DSIv2 blocks.

The initial read of REG_DSI_6G_HW_VERSION(offset 0x0) would result in a
read of REG_DSI_CTRL for DSIv2. This register won't necessarily be 0 on
DSIv2. It can be non zero if DSI was previously initialized by the
bootloader.

Instead of reading offset 0x0, we now read offset 0x1f0. For DSIv2, this
register is DSI_VERSION, and is bound to be non-zero. On DSI6G, this
register(offset 0x1f0) is SCRATCH_REGISTER_0, which no one ever seems to
touch, and from all register dumps I'vc seen, holds 0 all the time.

Modify dsi_get_version to read REG_DSI_VERSION to determine whether we
are DSI6G or DSIv2.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

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This commit is contained in:

Archit Taneja 2015-10-09 11:10:59 +05:30 • committed by Rob Clark

parent c6538de8dd

commit 648d506372

1 changed files with 18 additions and 6 deletions

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drivers/gpu/drm/msm/dsi/dsi_host.c

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