Kanchipuram is 70 kms from chennai, 36 kms from chengalpattu.How to reachRoute no 76 from MMDA bus stand from chennai takes you to Kanchi bus stand ( Theradi) From there catch an auto or town bus to Vishnu kanchi and before vishnu Kanchi is the sthalam or mandir. Persons from south can alight at Chengal pattu and catch a bus to kanchi and get down at Vishnu Kanchi. It stops at vishnu kanchi and the next stop is for Sonna Vannam Seitha perumal. ( The lord who did as you said).
Kani Kannan who is the foster brother of Tirumazhisai alwar was asked by the kanchi king to sing song by the alwar for money. But Kani Kannan replied that his brother never sing any song except about the lord. So the Raja asked kani Kannan to sing a song in praise of him. Since he also followed the same principle as that of his brother he also refused. So the king got furious and ordered both of them to leave Kanchipuram.
Kani kannan went and narrated the whole story to his brother. Thirumazhisai alwar sung a song on the Bhagawan
kanikannan pogindran kamuru punkachi
Manivanna Ni kidaka Vendi Thunivudaya
Chennapulaven naanum Poogindren Neeyum
Undan Pinaga payeyi Churuttikoll
Meaning
Kanikannan is going out of kanchi. So Iam also going. You also roll your blanket (Adiseshan) and come behind us. hearing this the lord also started to move behind alwar. they stayed at Orikai for one night.
The king went and pleaded the alwar to come back.
Kannikannan pokoindan kamaru punkachi
Manivanna Ni kidaka Vendi Thunivudaya
Chennapulavan Nanuum pokoindan Neeyum
Undan Pinaga Payeyi Virithu Koll.
It means Kani kannan is returning. I am also returning. You also roll back your blanket for sleeping. So the lord is called Sonna Vanum Seitha perumal. The lord sid as you said.
Moolavar and Thaayar:
The Moolavar of this sthalam is Sri Yathothakaari. Other names are Sonnavannam seitha Perumal and Vegasethu. Moolavar is in Kidantha Kolam (Bhujanga Sayanam), facing in West direction. Prathyaksham for Brahma Devan, Poigai, Bootham Alwar, Kanikannan. This perumal is found in Sleeping posture from right side to left. This is also one of the speciality of this Shetram.
Thaayar : Komalavalli Nachiyaar.
Utsavar Made with the combination of precious metal in which gold has a major part.
Sannadhis: Pilla logacharyar.
Mangalasasanam:
Thirumazhisai Alwar - 3 Pasuram
Thirumangai Alwar - 6 Pasuram
Poigai Alwar - 4 Pasuram
Nammalwar - 1 Pasuram
Total - 14