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Rockbox mail archiveSubject: Re: Feature freeze - silent play (wasRe: #673350 'Improvements for status line')Re: Feature freeze - silent play (wasRe: #673350 'Improvements for status line')
From: Mike Holden <rockbox_at_mikeholden.uklinux.net>
Date: Sat, 12 Apr 2003 20:26:56 +0100 (BST) Björn Stenberg said: > Mike Holden wrote: >> My remaining issue is "Silent Play". > > I believe silent play is an mpeg issue (misinterpreting vbr headers etc) > and not a disk reading issue. I also haven't seen any reports about this > since Linus fixed some problems in the mpeg code a while ago. Feel free > to brief us if this happens to you. Yes, I have still been seeing silent play. It ALWAYS happens towards the end of a track, and continues into the beginning of the next track. I see that a fix has just gone in for byte swapping, so I will investigate that, and report back if that doesn't fix it! >> The code comment has 5 * nop, and the comments says 400ms. Where did >> this figure come from? Is it the ATA spec? How long does a nop take, > > Yes, the 400ns is defined in the PIO protocol part of the ATA > specification: > > "HPIOI1: Check_Status State: > This state is entered when the host has written a PIO data-in command to > the device and nIEN is set to one, or when INTRQ is asserted. When in > this state, the host shall read the device Status register. When > entering this state from the HI4 state, the host shall wait 400 ns > before reading the Status register." > > A nop instruction takes one clock cycle, and since the cpu is clocked at > 12 MHz each cycle is 83ns long. Fair enough. Makes sense. Of course the FM has a slower CPU (11Mhz), so a NOP is therefore more like 90ns! Can't see that making any difference really. How much leeway do you get on the 400ns? Is it any time after that period? I assume it must be - it's just a minimum period to wait to give the hardware time to perform the operation and populate the register. -- Mike HoldenReceived on 2003-04-12 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |