Update specific attribute in jsf-primefaces

Question

I have two primeface calenders which are used to select "From" and "to" dates.I have set the max and min dates for the two calenders which are updated using the ajax dateSelect event so that the max date of "from" is never after the min date of "to" and the min date of "to" is never greater than the max date of "from" .My code is something similar to this.

<h:outputText value="From" />
 <p:calendar id="from" value="#{calendarBean.date1}" maxdate="#{calendarBean.date2}">  
        <p:ajax event="dateSelect" update="to"/>  
 </p:calendar>
 <h:outputText value="To" />
 <p:calendar id="to" value="#{calendarBean.date2}" mindate="#{calendarBean.date1}" maxdate="#{currDate}">  
        <p:ajax event="dateSelect" update="from"/>  
 </p:calendar>

The probleam is on every dateSelect many unnecessary calls are being made the backing bean i.e each attribute in "to" and "from" is getting updated while all i need is to update the max and mindates .Is there anyway i can update only the individual attributes like "maxdate" or "mindate" that would prevent unnecessary calls. Thanks in advance.