I have been trying to get a driver created for the TI Sitara am335xevm eval board. We have removed most of the circuit board stack that came with the eval board setup. Several board mod's later and we are connected to an FPGA eval board.
My device is up and running, we have writes 'working' however a read access does not generate any GPMC clock or other pin activity to the device. We would expect to at least see the address get driven on the bus.
I have correctly set my gpmc clock pin to input enabled. This seems to be the most common issue but did not pan out for us. We are not using gpmc_clk pin on the EVM board we have pin mux configuring the CSN1 pin to be our clock (AM335X_CTRL_PADCONF_GPMC_CSN1). the Register value is 0x00000021.
Chipselect region 0
GPMC Config 0_1:0x79001201
GPMC Config 0_2:0x00141400
GPMC Config 0_3:0x00060604
GPMC Config 0_4:0x120c140a
GPMC Config 0_5:0x02121a14
GPMC Config 0_6:0x900a0000
GPMC Config 0_7:0x00000848
Some of these settings I have broken out to command to let me change them 'on the fly' don't worry the code clears config reg7's enable bit then sets it after making any changes:
csOnTime:0
csWrOffTime:20
csRdOffTime:20
advOnTime:4
advWrOffTime:6
advRdOffTime:6
advExtraDelay:0
oeOnTime:12
oeExtraDelay:0
oeOffTime:20
weOnTime:12
weExtraDelay:0
weOffTime:18
wrCycleTime:26
wrAccessTime:16
rdCycleTime:20
rdAccessTime:18
pgBurstAccess:2
c2cDly:0
c2cSameCS:0
c2cDiffCS:0
busTurnTime:0
wrDataOnADMux:10
rd_acc_type:1
rd_type:1
gpmc_dev_pg_len:2
I don't believe this is a GPMC FSM timing violation, I have gone through the timing rules for the GPMC on this family of devices.
The other thing I find odd is that though our device is configured for 16 'word' access in the attached device page length field, we get only 8 word bursts. As noted in another thread here the cpu can only do 8 word accesses, eDMA is the only way to get 16 word. So it seems like the device page length field is more of a suggestion than a rule for the GPMC FSM. Maybe it is a rule for reads and suggestion for writes?
Any suggestions would be appreciated.
