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Commit 94a47c49 authored by Alex Deucher's avatar Alex Deucher
Browse files

drm/radeon: fix atom aux payload size check for writes (v2) 



The atom aux param interface only supports 4 bits for
the total write transfer size (header + payload).  This
limits us to 12 bytes of payload rather than 16.  Add a
check for this. Reads are not affected.

v2: switch to WARN_ON_ONCE

Reviewed-by: default avatarMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent dbfb00c3

drivers/gpu/drm/radeon/atombios_dp.c

+7 −0
Original line number Diff line number Diff line
@@ -178,6 +178,13 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) 
	switch (msg->request & ~DP_AUX_I2C_MOT) {

	case DP_AUX_NATIVE_WRITE:

	case DP_AUX_I2C_WRITE:

		/* The atom implementation only supports writes with a max payload of

		 * 12 bytes since it uses 4 bits for the total count (header + payload)

		 * in the parameter space.  The atom interface supports 16 byte

		 * payloads for reads. The hw itself supports up to 16 bytes of payload.

		 */

		if (WARN_ON_ONCE(msg->size > 12))

			return -E2BIG;

		/* tx_size needs to be 4 even for bare address packets since the atom

		 * table needs the info in tx_buf[3].

		 */