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* [PATCH][v2] driver/FSL SATA:Fix wrong Device Error Register usage
@ 2011-02-21  9:57 Prabhakar Kushwaha
  2011-03-02  3:25 ` Benjamin Herrenschmidt
  0 siblings, 1 reply; 5+ messages in thread
From: Prabhakar Kushwaha @ 2011-02-21  9:57 UTC (permalink / raw)
  To: linuxppc-dev; +Cc: meet2prabhu, B00888, Prabhakar Kushwaha

When a single device error is detected, the device under the error is indicated
by the error bit set in the DER. There is a one to one mapping between register
bit and devices on Port multiplier(PMP) i.e. bit 0 represents PMP device 0 and
bit 1 represents PMP device 1 etc.

Current implementation treats Device error register value as device number not
set of bits representing multiple device on PMP. It is changed to consider bit
level.
No need to check for each set bit as all command is going to be aborted.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale•com>
Signed-off-by: Ashish Kalra <B00888@freescale•com>
---
 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git (branch master)

 Changes for v1: Incorporated David Laight's comment
 	- Single usage of ffs()

 Changes for v2: Incorporated David Laight's comment
 	- Changed type of dev_num to unsigned

 drivers/ata/sata_fsl.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index b0214d0..895771c 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -1040,12 +1040,14 @@ static void sata_fsl_error_intr(struct ata_port *ap)
 
 		/* find out the offending link and qc */
 		if (ap->nr_pmp_links) {
+			unsigned int dev_num;
 			dereg = ioread32(hcr_base + DE);
 			iowrite32(dereg, hcr_base + DE);
 			iowrite32(cereg, hcr_base + CE);
 
-			if (dereg < ap->nr_pmp_links) {
-				link = &ap->pmp_link[dereg];
+			dev_num = ffs(dereg)-1;
+			if (dev_num < ap->nr_pmp_links) {
+				link = &ap->pmp_link[dev_num];
 				ehi = &link->eh_info;
 				qc = ata_qc_from_tag(ap, link->active_tag);
 				/*
-- 
1.7.3

^ permalink raw reply related	[flat|nested] 5+ messages in thread
* [PATCH][v2] driver/FSL SATA:Fix wrong Device Error Register usage
@ 2011-03-08  3:31 Prabhakar Kushwaha
  2011-03-08 11:39 ` David Laight
  0 siblings, 1 reply; 5+ messages in thread
From: Prabhakar Kushwaha @ 2011-03-08  3:31 UTC (permalink / raw)
  To: linux-ide
  Cc: meet2prabhu, Ashish Kalra, jgarzik, linuxppc-dev,
	Prabhakar Kushwaha

When a single device error is detected, the device under the error is indicated
by the error bit set in the DER. There is a one to one mapping between register
bit and devices on Port multiplier(PMP) i.e. bit 0 represents PMP device 0 and
bit 1 represents PMP device 1 etc.

Current implementation treats Device error register value as device number not
set of bits representing multiple device on PMP. It is changed to consider bit
level.
No need to check for each set bit as all command is going to be aborted.

Signed-off-by: Ashish Kalra <B00888@freescale•com>
Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale•com>
---

 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git (branch master)

 This patch is already gone through review of linuxppc-dev mail list.
 Making CC linuxppc-dev@lists•ozlabs.org

 Changes for v2: Incorporated Sergei Shtylyov's comment
	- Put space after -

 Case when ffs return will never arise.This scenario is already been discussed
 on linuxppc-dev@lists•ozlabs.org. Please see below explanation:
 sata_fsl_error_intr() is called during device error.The mentioned scenario
 will never comes. It can be observed via code:-
        if (cereg) {   --> cereg is set on command error. Means there is at least 1 device present.
                abort = 1;
                ---
                ---
                ---
                /* find out the offending link and qc */
                if (ap->nr_pmp_links) {  --> if Port multiplier
                        ---
                        ---
                        if ((ffs(dereg)-1) < ap->nr_pmp_links) {
                ---
                ---
                } else {  -->  Single device
                        dereg = ioread32(hcr_base + DE);
                        iowrite32(dereg, hcr_base + DE);
                        iowrite32(cereg, hcr_base + CE);

 drivers/ata/sata_fsl.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
index b0214d0..d71e7c2 100644
--- a/drivers/ata/sata_fsl.c
+++ b/drivers/ata/sata_fsl.c
@@ -1040,12 +1040,15 @@ static void sata_fsl_error_intr(struct ata_port *ap)
 
 		/* find out the offending link and qc */
 		if (ap->nr_pmp_links) {
+			unsigned int dev_num;
+
 			dereg = ioread32(hcr_base + DE);
 			iowrite32(dereg, hcr_base + DE);
 			iowrite32(cereg, hcr_base + CE);
 
-			if (dereg < ap->nr_pmp_links) {
-				link = &ap->pmp_link[dereg];
+			dev_num = ffs(dereg) - 1;
+			if (dev_num < ap->nr_pmp_links) {
+				link = &ap->pmp_link[dev_num];
 				ehi = &link->eh_info;
 				qc = ata_qc_from_tag(ap, link->active_tag);
 				/*
-- 
1.7.3

^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-03-08 11:42 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-02-21  9:57 [PATCH][v2] driver/FSL SATA:Fix wrong Device Error Register usage Prabhakar Kushwaha
2011-03-02  3:25 ` Benjamin Herrenschmidt
2011-03-02  5:22   ` Kushwaha Prabhakar-B32579
  -- strict thread matches above, loose matches on Subject: below --
2011-03-08  3:31 Prabhakar Kushwaha
2011-03-08 11:39 ` David Laight

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