Hello Vinod,
On 6/19/2018 9:52 PM, Vinod wrote:
Hi Rohit,
On 19-06-18, 19:20, Rohit Kumar wrote:
On 6/19/2018 10:35 AM, Vinod wrote:
On 18-06-18, 16:46, Rohit kumar wrote:
+struct sdm845_snd_data {
+ struct snd_soc_card *card;
+ struct regulator *vdd_supply;
+ struct snd_soc_dai_link dai_link[];
+};
+
+static struct mutex pri_mi2s_res_lock;
+static struct mutex quat_tdm_res_lock;
any reason why the locks can't be part of sdm845_snd_data?
Also why do we need two locks ?
No specific reason, I will move it to sdm845_snd_data.
These locks are used to protect enable/disable of bit clocks. We have
Primary MI2S RX/TX
and Quaternary TDM RX/TX interfaces. For primary mi2s rx/tx, we have single
clock which is
synchronized with pri_mi2s_res_lock. For Quat TDM RX/TX, we are using
quat_tdm_res_lock.
We need two locks as we are protecting two different resources.
I think bigger question is why do you need any locks? What is the race
scenario you envision which needs protection
Below is one of the race condition:
Thread1 | Thread2
----------------------------------------------------------
startup() |
count++; | startup()
read count (count = 1) |
enable_clock() | count++; //count = 2
shutdown() |
count--;// count = 1 |
| read count (count = 1)
| enable_clock()
Here clock will be enabled twice but disable will be called only once
when count = 0.
This will make the clock always enabled. So, I think we should keep
either mutex lock or atomic variable to synchronize this.
Regards,
Rohit
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