cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Highlighted
Adventurer
Adventurer
5,432 Views
Registered: ‎09-30-2014

Zynq CPU_1X max speed question - Appears to not function about 133 MHz on -3 speed grade parts

Jump to solution

We have a custom design using a Zynq 7020 -3 speed grade part.  We are using U-Boot as our secondary boot loader.  We have a test project in Vivado that simply instantiates the processor.  We have set the processor up using the 6:2:1 clocking mode with an external 33.3333 Mhz oscillator.  When we target the CPU frequency of anything above 783 MHz, the SD controller functionality breaks.  It appears to correspond to when the CPU_1X frequency feeding the SD/SDIO controller goes above 133 MHz.

 

According to DS187, the upper CPU_1X supported on a -3 part is 144 MHz.  We have validated that the IO PLL registers and the SD Clock Control Register is setup correctly.  That is why we are back to looking at the CPU_1X frequency. 

 

We have tried on multiple boards with the same problem.  Does someone have any insight?  We need to run above the 783 MHz CPU frequency, but can't until we get this resolved.

0 Kudos
1 Solution

Accepted Solutions
Highlighted
Adventurer
Adventurer
9,787 Views
Registered: ‎09-30-2014

It turns out to be a U-Boot driver issue when running the processor CPU frequency about 783 MHz.

 

U-Boot bug reported in Embedded Forum

View solution in original post

0 Kudos
2 Replies
Highlighted
Adventurer
Adventurer
5,421 Views
Registered: ‎09-30-2014

What I have observed is that the output of the SD controller seems to work correctly in both the slower and faster clock frequencies.  The controller succesfully is set to output a SD clk of 196 kHZ.  The only difference is that the SDHCI reports an error when the CPU_1X frequency is greater than 133 MHz.

0 Kudos
Highlighted
Adventurer
Adventurer
9,788 Views
Registered: ‎09-30-2014

It turns out to be a U-Boot driver issue when running the processor CPU frequency about 783 MHz.

 

U-Boot bug reported in Embedded Forum

View solution in original post

0 Kudos