Commit b44b9bc7 authored by Neil Armstrong's avatar Neil Armstrong Committed by Viresh Kumar
Browse files

OPP: fix dev_pm_opp_find_bw_*() when bandwidth table not initialized 



If a driver calls dev_pm_opp_find_bw_ceil/floor() the retrieve bandwidth
from the OPP table but the bandwidth table was not created because the
interconnect properties were missing in the OPP consumer node, the
kernel will crash with:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004
...
pc : _read_bw+0x8/0x10
lr : _opp_table_find_key+0x9c/0x174
...
Call trace:
  _read_bw+0x8/0x10 (P)
  _opp_table_find_key+0x9c/0x174 (L)
  _find_key+0x98/0x168
  dev_pm_opp_find_bw_ceil+0x50/0x88
...

In order to fix the crash, create an assert function to check
if the bandwidth table was created before trying to get a
bandwidth with _read_bw().

Fixes: add1dc09 ("OPP: Use generic key finding helpers for bandwidth key")
Signed-off-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
parent d659bc68

drivers/opp/core.c

+13 −2
Original line number Diff line number Diff line
@@ -116,6 +116,15 @@ static bool assert_clk_index(struct opp_table *opp_table, 
	return opp_table->clk_count > index;

}



/*

 * Returns true if bandwidth table is large enough to contain the bandwidth index.

 */

static bool assert_bandwidth_index(struct opp_table *opp_table,

				   unsigned int index)

{

	return opp_table->path_count > index;

}



/**

 * dev_pm_opp_get_bw() - Gets the bandwidth corresponding to an opp

 * @opp:	opp for which bandwidth has to be returned for
@@ -915,7 +924,8 @@ struct dev_pm_opp *dev_pm_opp_find_bw_ceil(struct device *dev, unsigned int *bw, 
	unsigned long temp = *bw;

	struct dev_pm_opp *opp;



	opp = _find_key_ceil(dev, &temp, index, true, _read_bw, NULL);

	opp = _find_key_ceil(dev, &temp, index, true, _read_bw,

			     assert_bandwidth_index);

	*bw = temp;

	return opp;

}
@@ -946,7 +956,8 @@ struct dev_pm_opp *dev_pm_opp_find_bw_floor(struct device *dev, 
	unsigned long temp = *bw;

	struct dev_pm_opp *opp;



	opp = _find_key_floor(dev, &temp, index, true, _read_bw, NULL);

	opp = _find_key_floor(dev, &temp, index, true, _read_bw,

			      assert_bandwidth_index);

	*bw = temp;

	return opp;

}