enabling ad9144 as a module

Question

Hi, 
 
 I'm trying to debug a setup with an ad9136 and to help with this, we're trying to build all the drivers associated with this chip as modules. 
 I was wondering if this has been tried before and if there are things I should be careful about. 
 At the moment, it looks like I might have an issue with the order in which the modules are loaded. 
 Thanks for your time, 
 Liam

lvb · Accepted Answer

Hi , 
 Unknown said: Maybe check that the clock is enabled (clk_prepare_enable() called) before reading anything from the IP core. 
 Thanks for this suggestion, it seems to have fixed my issue! I've submitted a draft pull request to fix this in the axi-clkgen driver. 
 Simply adding a reference to the axi_clk in the axi_quad_spi node fixed the issue with that driver too. 
 Thanks again for your help, 
 Liam)

ADIApproved · Answer

With which version was this working before? 
 
 lvb said: Also, We're debugging using modules because the kernel seems to hang when accessing some AXI IP cores. Is that something you've seen before? 
 
 It's not unheard of that in some setups the probe order can influence behavior. 
 Usually for the IP cores to be able to read regs, the axi-clk needs to be enabled. This can be done in the driver, or the core can have this enabled by default. 
 Maybe check that the clock is enabled (clk_prepare_enable() called) before reading anything from the IP core. 
 
 One example is: 
 https://github.com/analogdevicesinc/linux/commit/d78a31ef3583d58f8af9a6a385bc6308f897496c#diff-4024e54ca1569d5a29c5abc04ffbb1a2 
 
 Someone else had some issue with a kernel hang (with our spi-axi-engine), because in some setups, the clock isn't enabled early in the probe. 
 
 No idea if this also fixes this for you, but maybe do a check for this.

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enabling ad9144 as a module