On Thu, 08 May 2025, "Lin, Wayne" Wayne.Lin@amd.com wrote:
[Public]
-----Original Message----- From: Jani Nikula jani.nikula@intel.com Sent: Thursday, May 8, 2025 4:19 PM To: Lin, Wayne Wayne.Lin@amd.com; dri-devel@lists.freedesktop.org Cc: ville.syrjala@linux.intel.com; Limonciello, Mario Mario.Limonciello@amd.com; Wentland, Harry Harry.Wentland@amd.com; Lin, Wayne Wayne.Lin@amd.com; stable@vger.kernel.org Subject: Re: [PATCH] drm/dp: Fix Write_Status_Update_Request AUX request format
On Sun, 27 Apr 2025, Wayne Lin Wayne.Lin@amd.com wrote:
/** When I2C write firstly get defer and get ack after* retries by wirte_status_update, we have to return* all data bytes get transferred instead of 0.*/My brain gives me syntax and parse error here. ;)
Appreciate for the feedback, Jani. Could you elaborate more on your concerns please?
Since Write_Status_Update_Request is address only request. Data length is 0. When I2C write request completes, reply for Write_Status_Update_Request from DPRx will be ACK only (i.e. data length is 0).
Is your concern about returning 0 from aux->transfer? My thoughts is drm_dp_i2c_do_msg() is designed to handle I2C-Over-Aux reply data, and aux->transfer() is handling hw specific manipulation and return transferred bytes. For Write_Status_Update_Request request itself, nothing new to be transferred. I think drm_dp_i2c_do_msg() should be responsible for determining the correct transferred data bytes under this case. Or do you expect aux->transfer to memorize the data length of write request?
My concern is that I don't understand what the comment is trying to say.
"when i2c write firstly get defer" - what does it mean?
"wirte_status_update" - typo
"we have to" - why?
"return all data bytes get transferred" - what does it mean?
Thanks!
BR, Jani.
-- Jani Nikula, Intel
-- Wayne Lin