[Python] Get all the rows with max value in a pandas dataframe column in Python

I have a pandas dataframe with following columns.

col1 col2 col3 col4
A101 3 LLT 10028980
A101 7 LLT 10028980
A101 7 PT 10028980
A102 5 LLT 10028981
A102 3 PT 10028981
A103 2 PT 10028982
A103 4 LLT 10028982


I would like to extract all those rows where col2 is max for each value of col1. The expected output is:

col1 col2 col3 col4
A101 7 LLT 10028980
A101 7 PT 10028980
A102 5 LLT 10028981
A103 4 LLT 10028982


I am using following lines of code but it is filtering the rows where there are multiple rows with max value (row 1 is excluded).

m = df.notnull().all(axis=1)

df = df.loc[m].groupby('col1').max().reset_index()

I am getting this output:

col1 col2 col3 col4
A101 7 PT 10028980
A102 5 LLT 10028981
A103 4 LLT 10028982

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