Qspi frequency test fix

[maciejbocianski]

Description

• fix qspi_frequency_test: prevent setting frequency below QSPI_MIN_FREQUENCY
• adjust min frequency for EFM32GG11 target for hal qspi test

Pull request type

[ ] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[X] Test update
[ ] Breaking change

Reviewers

@jamesbeyond

Release Notes

[ciarmcom]

@maciejbocianski, thank you for your changes.
@jamesbeyond @ARMmbed/mbed-os-test @ARMmbed/mbed-os-hal @ARMmbed/mbed-os-maintainers please review.

[0xc0170]

Why this min is set to the value 2000000?

[0xc0170]

Reviewers please look at this PR

[0xc0170]

I scheduled CI to get early test results

[mbed-ci]

Test run: SUCCESS

Summary: 5 of 5 test jobs passed
Build number : 1
Build artifacts

[0xc0170]

Tests completed.

Why this min is set to the value 2000000?

@maciejbocianski Can you answer?

Also reviewers review, lets take this in soon.

[maciejbocianski]

Setting frequency below 2MHz cause that basediv gets value larger then allowed max causing undefined behavior and errors in following testcases.

mbed-os/targets/TARGET_Silicon_Labs/TARGET_EFM32/emlib/inc/em_qspi.h

Lines 188 to 197 in 9534327

	/** QSPI initialization structure. */
	typedef struct {
	/** Enable/disable Quad SPI when initialization is completed. */
	bool enable;
	/**
	* Master mode baude rate divisor. Values can be even numbers in the range
	* [2-32] inclusive. */
	uint8_t divisor;
	} QSPI_Init_TypeDef;

[0xc0170]

Restarted CI

We shall progress with this fix today.

[mbed-ci]

Test run: SUCCESS

Summary: 5 of 5 test jobs passed
Build number : 2
Build artifacts