Re: [PATCH 12/21] ata: libahci: Discard redundant force_port_map parameter

Damien Le Moal
2022-03-24T02:06:08Z

On 3/24/22 09:16, Serge Semin wrote:
> Currently there are four port-map-related fields declared in the
> ahci_host_priv structure and used to setup the HBA ports mapping. First
> the ports-mapping is read from the PI register and immediately stored in
> the saved_port_map field. If forced_port_map is initialized with non-zero
> value then its value will have greater priority over the value read from
> PI, thus it will override the saved_port_map field. That value will be then
> masked by a non-zero mask_port_map field and after some sanity checks it
> will be stored in the ahci_host_priv.port_map field as a final port
> mapping.
>
> As you can see the logic is a bit too complicated for such a simple task.
> We can freely get rid from at least one of the fields with no change to
> the implemented semantic. The force_port_map field can be replaced with
> taking non-zero saved_port_map value into account. So if saved_port_map is
> pre-initialized by the glue-driver/platform-specific code then it will

glue-driver == LLDD (low level device driver), for the entire series please.

> have greater priority over the value read from PI register and will be
> used as actual HBA ports mapping later on. Thus the ports map forcing task
> will be just transferred from the force_port_map to saved_port_map field.
>
> This modification will perfectly fit into the feature of having OF-based
> initialization of the HW-init HBA CSR fields we are about to introduce in
> the next commit.
>
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
> drivers/ata/ahci.c | 2 +-
> drivers/ata/ahci.h | 1 -
> drivers/ata/libahci.c | 10 ++++++----
> drivers/ata/libahci_platform.c | 2 +-
> 4 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index ab5811ef5a53..8ce0d166cc8d 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -654,7 +654,7 @@ static void ahci_pci_save_initial_config(struct pci_dev *pdev,
> {
> if (pdev->vendor == PCI_VENDOR_ID_JMICRON && pdev->device == 0x2361) {
> dev_info(&pdev->dev, "JMB361 has only one port\n");
> - hpriv->force_port_map = 1;
> + hpriv->saved_port_map = 1;
> }
>
> /*
> diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
> index 04690b4168a3..519d148ecaea 100644
> --- a/drivers/ata/ahci.h
> +++ b/drivers/ata/ahci.h
> @@ -329,7 +329,6 @@ struct ahci_port_priv {
> struct ahci_host_priv {
> /* Input fields */
> unsigned int flags; /* AHCI_HFLAG_* */
> - u32 force_port_map; /* force port map */
> u32 mask_port_map; /* mask out particular bits */
>
> void __iomem * mmio; /* bus-independent mem map */
> diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
> index 0ed484e04fd6..011175e82174 100644
> --- a/drivers/ata/libahci.c
> +++ b/drivers/ata/libahci.c
> @@ -453,7 +453,6 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> * reset. Values without are used for driver operation.
> */
> hpriv->saved_cap = cap = readl(mmio + HOST_CAP);
> - hpriv->saved_port_map = port_map = readl(mmio + HOST_PORTS_IMPL);
>
> /* CAP2 register is only defined for AHCI 1.2 and later */
> vers = readl(mmio + HOST_VERSION);
> @@ -517,10 +516,13 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
> cap &= ~HOST_CAP_SXS;
> }
>
> - if (hpriv->force_port_map && port_map != hpriv->force_port_map) {
> + /* Override the HBA ports mapping if the platform needs it */
> + port_map = readl(mmio + HOST_PORTS_IMPL);
> + if (hpriv->saved_port_map && port_map != hpriv->saved_port_map) {
> dev_info(dev, "forcing port_map 0x%x -> 0x%x\n",
> - port_map, hpriv->force_port_map);
> - port_map = hpriv->force_port_map;
> + port_map, hpriv->saved_port_map);
> + port_map = hpriv->saved_port_map;
> + } else {
> hpriv->saved_port_map = port_map;
> }
>
> diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c
> index febad33aa43c..5cbc2c42164d 100644
> --- a/drivers/ata/libahci_platform.c
> +++ b/drivers/ata/libahci_platform.c
> @@ -539,7 +539,7 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev,
> }
>
> of_property_read_u32(dev->of_node,
> - "ports-implemented", &hpriv->force_port_map);
> + "ports-implemented", &hpriv->saved_port_map);
>
> if (child_nodes) {
> for_each_child_of_node(dev->of_node, child) {

--
Damien Le Moal
Western Digital Research