On Thu, Feb 01, 2024 at 01:10:05PM +0800, Choong Yong Liang wrote:

On 30/1/2024 6:21 pm, Russell King (Oracle) wrote:

quoted

NAK. Absolutely not. You haven't read the phylink documentation, nor
understood how phylink works.

Since you haven't read the phylink documentation, I'm not going to
waste any more time reviewing this series since you haven't done your
side of the bargin here.

Hi Russell,

Sorry that previously I only studied the phylink based on the `phylink.h`
itself.

From phylink.h:

/**
 * mac_select_pcs: Select a PCS for the interface mode.
 * @config: a pointer to a &struct phylink_config.
 * @interface: PHY interface mode for PCS
 *
 * Return the &struct phylink_pcs for the specified interface mode, or
 * NULL if none is required, or an error pointer on error.
 *
 * This must not modify any state. It is used to query which PCS should
 * be used. Phylink will use this during validation to ensure that the
 * configuration is valid, and when setting a configuration to internally
 * set the PCS that will be used.
 */

Note the "This must not modify any state." statement. By reinitialising
the PCS in this method, you are violating that statement.

This requirement is because this method will be called by
phylink_validate_mac_and_pcs() at various times, potentially for each
and every interface that stmmac supports, which will lead to you
reinitialising the PCS, killing the link, each time we ask the MAC for
a PCS, whether we are going to make use of it in that mode or not.

You can not do this. Sorry. Hard NAK for this approach.

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