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@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Naveen Naidu <naveennaidu479@gmail.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..0f732ba2f71a 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)							\
+		SET_PCI_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)							\
+		SET_PCI_ERROR_RESPONSE(val);				\
+	else								\
+		*val = (type)data;					\
 	return pcibios_err_to_errno(ret);				\
 }									\
 EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
-- 
2.25.1

On Thursday 21 October 2021 20:37:27 Naveen Naidu wrote:
> 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@kernel.org>
> Reviewed-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>

Reviewed-by: Pali Rohár <pali@kernel.org>

> ---
>  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..0f732ba2f71a 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)							\
> +		SET_PCI_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)							\
> +		SET_PCI_ERROR_RESPONSE(val);				\
> +	else								\
> +		*val = (type)data;					\
>  	return pcibios_err_to_errno(ret);				\
>  }									\
>  EXPORT_SYMBOL_GPL(pci_user_read_config_##size);
> -- 
> 2.25.1
>