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Commit ff639e1c authored by Harshdeep Dhatt's avatar Harshdeep Dhatt
Browse files

msm: kgsl: Retry rbbm batch register read 



On a650, it's possible that a valid register read in the
batch register block inside rbbm may return 0xdeafbead. Retry
few times until you get back the actual register value.

Change-Id: I010899b876487fdcb61dfcfda89cc0c109735f72
Signed-off-by: default avatarHarshdeep Dhatt <hdhatt@codeaurora.org>
parent 648dc229

drivers/gpu/msm/adreno.c

+49 −0
Original line number Diff line number Diff line
@@ -2941,6 +2941,50 @@ static void adreno_read(struct kgsl_device *device, void __iomem *base, 
	rmb();

}



static void adreno_retry_rbbm_read(struct kgsl_device *device,

		void __iomem *base, unsigned int offsetwords,

		unsigned int *value, unsigned int mem_len)

{

	int i;

	void __iomem *reg;



	/* Make sure we're not reading from invalid memory */

	if (WARN(offsetwords * sizeof(uint32_t) >= mem_len,

		"Out of bounds register read: 0x%x/0x%x\n",

		offsetwords, mem_len >> 2))

		return;



	reg = (base + (offsetwords << 2));



	/*

	 * If 0xdeafbead was transient, second read is expected to return the

	 * actual register value. However, if a register value is indeed

	 * 0xdeafbead, read it enough times to guarantee that.

	 */

	for (i = 0; i < 16; i++) {

		*value = readl_relaxed(reg);

		/*

		 * Read barrier needed so that register is read from hardware

		 * every iteration

		 */

		rmb();



		if (*value != 0xdeafbead)

			return;

	}

}



static inline bool adreno_is_a650_rbbm_batch_reg(unsigned int offsetwords)

{

	if (((offsetwords > 0x0) && (offsetwords < 0x3FF)) ||

		((offsetwords > 0x4FA) && (offsetwords < 0x53F)) ||

		((offsetwords > 0x556) && (offsetwords < 0x5FF)) ||

		((offsetwords > 0xF400) && (offsetwords < 0xFFFF)))

		return  true;



	return false;

}



/**

 * adreno_regread - Used to read adreno device registers

 * @offsetwords - Word (4 Bytes) offset to the register to be read
@@ -2951,6 +2995,11 @@ static void adreno_regread(struct kgsl_device *device, unsigned int offsetwords, 
{

	adreno_read(device, device->reg_virt, offsetwords, value,

						device->reg_len);



	if ((*value == 0xdeafbead) && adreno_is_a650(ADRENO_DEVICE(device)) &&

		adreno_is_a650_rbbm_batch_reg(offsetwords))

		adreno_retry_rbbm_read(device, device->reg_virt, offsetwords,

			value, device->reg_len);

}



/**