drm/i915: cope with large i2c transfers
Subsystems (2)
PATCH v2 1/1 drm/i915: cope with large i2c transfers
The hardware, according to the specs, is limited to 256 byte transfers, and current driver has no protections in case users attempt to do larger transfers. The code will just stomp over status register and mayhem ensues.
Let's split larger transfers into digestable chunks. Doing this allows Atmel MXT driver on Pixel 1 function properly (it hasn't since commit 9d8dc3e529a19e427fd379118acd132520935c5d "Input: atmel_mxt_ts - implement T44 message handling" which tries to consume multiple touchscreen/touchpad reports in a single transaction).
---
V2: reduced the limit from 511 to 256, added stable designation.
drivers/gpu/drm/i915/i915_reg.h | 1 + drivers/gpu/drm/i915/intel_i2c.c | 66 ++++++++++++++++++++++++++++++++++------ 2 files changed, 57 insertions(+), 10 deletions(-)
drivers/gpu/drm/i915/i915_reg.h +1 -0
@@ -1807,6 +1807,7 @@ enum skl_disp_power_wells {#define GMBUS_CYCLE_INDEX (2<<25)#define GMBUS_CYCLE_STOP (4<<25)#define GMBUS_BYTE_COUNT_SHIFT 16 +#define GMBUS_BYTE_COUNT_MAX 256U#define GMBUS_SLAVE_INDEX_SHIFT 8#define GMBUS_SLAVE_ADDR_SHIFT 1#define GMBUS_SLAVE_READ (1<<0)
drivers/gpu/drm/i915/intel_i2c.c +56 -10
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Signature · 4 lines
2.2.0.rc0.207.ga3a616c -- Dmitry
Quoted 4 lines · Dmitry Torokhov
The hardware, according to the specs, is limited to 256 byte transfers, and current driver has no protections in case users attempt to do larger transfers. The code will just stomp over status register and mayhem ensues.
Thanks, looks good.
David/Daniel - should I take this directly, or can I expect to just get it from the drm tree?
Linus
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Quoted 11 lines · Linus Torvalds
Quoted 4 lines · Dmitry Torokhov
The hardware, according to the specs, is limited to 256 byte transfers, and current driver has no protections in case users attempt to do larger transfers. The code will just stomp over status register and mayhem ensues.
Thanks, looks good.
David/Daniel - should I take this directly, or can I expect to just get it from the drm tree?
I asked Jani to pick this up. I'm horribly jetlagged and just repacking for my vacation so probably shouldn't touch git branches right now ;-) -Daniel
Signature · 7 lines
Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Quoted 8 lines · Daniel Vetter
Quoted 7 lines · Linus Torvalds
Quoted 4 lines · Dmitry Torokhov
The hardware, according to the specs, is limited to 256 byte transfers, and current driver has no protections in case users attempt to do larger transfers. The code will just stomp over status register and mayhem ensues.
Quoted 7 lines
Quoted 4 lines
Thanks, looks good.
David/Daniel - should I take this directly, or can I expect to just get it from the drm tree?
I asked Jani to pick this up. I'm horribly jetlagged and just repacking for my vacation so probably shouldn't touch git branches right now ;-)
Pushed to drm-intel-next-fixes, thanks for the patch and review. I'll gather a few more fixes and send the pull req to Dave later.
BR,
Jani.
Quoted 9 lines
-Daniel
Signature · 7 lines
Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Signature · 1 line
Jani Nikula, Intel Open Source Technology Center