GSM Dome quotes Chinese market analysts saying that a lot of Sony image sensor production capacity has been allocated for Apple iPhone 6c, supposed to be launched in September. Due to that, smartphone companies in China are unable to get enough Sony image sensors for their products. Huawei is said to manage to ship just 50% of its devices with Sony sensors, while ZTE, Oppo and Coolpad are able to get just 10-30% smartphones on the market with a Sony camera module.
As a result, these companies are forced to go to Samsung, Toshiba or Omnivision to complement their supply of image sensors. It is speculated that HTC has chosen Toshiba sensors for its HTC One M8 for that reason as well.
Update: Digitimes sources in Taiwan generally confirm the story. Sony gives priority supply to Apple and Samsung. Supplies of Sony's CMOS image sensors are at least 30% short of demand for China's smartphone vendors including Xiaomi, Huawei, Coolpad and ZTE, according to the newspaper's sources. For some second- and third-tier vendors, the shortage is as high as 70-80% due to a lack of purchasing bargain power.