| Message ID | 20171207102003.23496-2-asolokha@kb.kras.ru |
|---|---|
| State | Accepted |
| Headers | show |
| Series | i2c: mpc: Clean up clock selection | expand |
On Thu, Dec 07, 2017 at 05:20:00PM +0700, Arseny Solokha wrote: > Obtaining the actual I2C clock prescaler value in mpc_i2c_setup_8xxx() only > happens when the clock parameter is set to something other than > MPC_I2C_CLOCK_LEGACY. When the clock parameter is exactly > MPC_I2C_CLOCK_LEGACY, the prescaler parameter is used in arithmetic > division as provided by the caller, resulting in a division by zero > for the majority of processors supported by the module. > > Avoid division by zero by obtaining the actual I2C clock prescaler > in mpc_i2c_setup_8xxx() unconditionally regardless of the passed clock > value. > > Signed-off-by: Arseny Solokha <asolokha@kb.kras.ru> Applied to for-current, thanks!
On Sat, Dec 30, 2017 at 07:18:14PM +0100, Wolfram Sang wrote: > On Thu, Dec 07, 2017 at 05:20:00PM +0700, Arseny Solokha wrote: > > Obtaining the actual I2C clock prescaler value in mpc_i2c_setup_8xxx() only > > happens when the clock parameter is set to something other than > > MPC_I2C_CLOCK_LEGACY. When the clock parameter is exactly > > MPC_I2C_CLOCK_LEGACY, the prescaler parameter is used in arithmetic > > division as provided by the caller, resulting in a division by zero > > for the majority of processors supported by the module. > > > > Avoid division by zero by obtaining the actual I2C clock prescaler > > in mpc_i2c_setup_8xxx() unconditionally regardless of the passed clock > > value. > > > > Signed-off-by: Arseny Solokha <asolokha@kb.kras.ru> > > Applied to for-current, thanks! Reconsidered and moved to for-next.
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 950a9d74f54d..6ad87555f71e 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -382,18 +382,18 @@ static int mpc_i2c_get_fdr_8xxx(struct device_node *node, u32 clock, u32 divider; int i; - if (clock == MPC_I2C_CLOCK_LEGACY) { - /* see below - default fdr = 0x1031 -> div = 16 * 3072 */ - *real_clk = fsl_get_sys_freq() / prescaler / (16 * 3072); - return -EINVAL; - } - /* Determine proper divider value */ if (of_device_is_compatible(node, "fsl,mpc8544-i2c")) prescaler = mpc_i2c_get_sec_cfg_8xxx() ? 3 : 2; if (!prescaler) prescaler = mpc_i2c_get_prescaler_8xxx(); + if (clock == MPC_I2C_CLOCK_LEGACY) { + /* see below - default fdr = 0x1031 -> div = 16 * 3072 */ + *real_clk = fsl_get_sys_freq() / prescaler / (16 * 3072); + return -EINVAL; + } + divider = fsl_get_sys_freq() / clock / prescaler; pr_debug("I2C: src_clock=%d clock=%d divider=%d\n",
Obtaining the actual I2C clock prescaler value in mpc_i2c_setup_8xxx() only happens when the clock parameter is set to something other than MPC_I2C_CLOCK_LEGACY. When the clock parameter is exactly MPC_I2C_CLOCK_LEGACY, the prescaler parameter is used in arithmetic division as provided by the caller, resulting in a division by zero for the majority of processors supported by the module. Avoid division by zero by obtaining the actual I2C clock prescaler in mpc_i2c_setup_8xxx() unconditionally regardless of the passed clock value. Signed-off-by: Arseny Solokha <asolokha@kb.kras.ru> --- drivers/i2c/busses/i2c-mpc.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)