From: Bartlomiej Zolnierkiewicz Date: Tue, 5 Jan 2010 07:07:27 +0000 (+0000) Subject: icside: bring back ->maskproc method X-Git-Tag: v2.6.34-rc1~203^2^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f75d4a238770d83d3a0475ce7f34e3fa37de161e;p=pandora-kernel.git icside: bring back ->maskproc method Bring back ->maskproc method since it is still needed for proper operation, as noticed by Russell King: > This change is bogus. > > writeb(0, base + ICS_ARCIN_V6_INTROFFSET_1); > readb(base + ICS_ARCIN_V6_INTROFFSET_2); > > writeb(0, base + ICS_ARCIN_V6_INTROFFSET_2); > readb(base + ICS_ARCIN_V6_INTROFFSET_1); > > This sequence of code does: > > 1. enable interrupt 1 > 2. disable interrupt 2 > 3. enable interrupt 2 > 4. disable interrupt 1 > > which results in the interrupt for the second channel being enabled - > leaving channel 1 blocked. > > Firstly, icside shares its two IDE channels with one DMA engine - so it's > a simplex interface. IDE supports those (or did when the code was written) > serializing requests between the two interfaces. libata does not. > > Secondly, the interrupt lines on icside float when there's no drive connected > or when the drive has its NIEN bit set, which means that you get spurious > screaming interrupts which can kill off all expansion card interrupts on > the machine unless you disable the channel interrupt on the card. > > Since libata can not serialize the operation of the two channels like IDE > can, the libata version of the icside driver does not contain the interrupt > stearing logic. Instead, it looks at the status after reset, and if > nothing was found on that channel, it masks the interrupt from that > channel. This patch reverts changes done in commit dff8817 (I became confused due to non-standard & undocumented ->maskproc method, anyway sorry about that). Noticed-by: Russell King Signed-off-by: Bartlomiej Zolnierkiewicz Signed-off-by: David S. Miller --- Reading git-diff-tree failed