akpm@xxxxxxxxxxxxxxxxxxxx wrote:
From: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> 2.6.21-rc has horrible problems with libata and PATA cable types (and thus speeds). This occurs because Tejun fixed a pile of other bugs and we now do cable detect enforcement for drive side detection properly. Unfortunately we don't do the process around cable detection right. Tejun identified the problem and pointed to the right Annex in the spec, this patch implements the needed changes. The basic requirement is that we have to identify the slave before the master. The patch switches the identify order so that we can do the drive side detection correctly. Secondly we add a ->cable_detect() method called after the identify sequence which allows a host to do host side detection at this point should it wish, or to modify the results of the drive side identify. This separate ->cable_detect method also cleans up a lot of code because many drivers have their own error_handler methods which really just set the cable type. If there is no ->cable_detect method the cable type is left alone so a driver setting it earlier (eg because it has the SATA flags set or because it uses the old error_handler approach) will still do the right thing (or at least the same thing) as before. This patch simply adds the cable_detect method and helpers it doesn't use them but other follow up patches will (ie Adrian please don't submit patches to unexport them ;)) Signed-off-by: Alan Cox <alan@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/ata/libata-core.c | 59 ++++++++++++++++++++++++++++++++++++ include/linux/libata.h | 7 ++++ 2 files changed, 66 insertions(+)
applied to #upstream, after fixing the patch description to reflect the loss of half of the original patch's functionality
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