linux-kernel - [PATCH v4 02/25] PCI: Set error response in config access defines when ops->read() fails

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Message-Id: <4188fc5465631ce0d472d1423de3d9fb2f09b8ff.1637243717.git.naveennaidu479@gmail.com>
Date:   Thu, 18 Nov 2021 19:33:12 +0530
From:   Naveen Naidu <naveennaidu479@...il.com>
To:     bhelgaas@...gle.com
Cc:     Naveen Naidu <naveennaidu479@...il.com>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org, Rob Herring <robh@...nel.org>,
        Pali Rohár <pali@...nel.org>
Subject: [PATCH v4 02/25] PCI: Set error response in config access defines when ops->read() fails

Make PCI_OP_READ and PCI_USER_READ_CONFIG set the data value with error
response (~0), when the PCI device read by a host controller fails.

This ensures that the controller drivers no longer need to fabricate
(~0) value when they detect error. It also  gurantees that the error
response (~0) is always set when the controller drivers fails to read a
config register from a device.

This makes error response fabrication consistent and helps in removal of
a lot of repeated code.

Suggested-by: Rob Herring <robh@...nel.org>
Reviewed-by: Rob Herring <robh@...nel.org>
Reviewed-by: Pali Rohár <pali@...nel.org>
Signed-off-by: Naveen Naidu <naveennaidu479@...il.com>
---
 drivers/pci/access.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index 46935695cfb9..eac0765d8bed 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -42,7 +42,10 @@ int noinline pci_bus_read_config_##size \
 	if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;	\
 	pci_lock_config(flags);						\
 	res = bus->ops->read(bus, devfn, pos, len, &data);		\
-	*value = (type)data;						\
+	if (res)							\
+		PCI_SET_ERROR_RESPONSE(value);				\
+	else								\
+		*value = (type)data;					\
 	pci_unlock_config(flags);					\
 	return res;							\
 }
@@ -228,7 +231,10 @@ int pci_user_read_config_##size						\
 	ret = dev->bus->ops->read(dev->bus, dev->devfn,			\
 					pos, sizeof(type), &data);	\
 	raw_spin_unlock_irq(&pci_lock);				\
-	*val = (type)data;						\
+	if (ret)							\
+		PCI_SET_ERROR_RESPONSE(val);				\
+	else								\
+		*val = (type)data;					\
 	return pcibios_err_to_errno(ret);				\
 }									\
 EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
-- 
2.25.1