Re: [PATCH v1 2/3] PCI / ACPI: Remove the need for 'struct hotplug_params'

Bjorn Helgaas
2019-04-19T20:07:45Z

On Fri, Feb 08, 2019 at 10:24:12AM -0600, Alexandru Gagniuc wrote:
> We used to first parse all the _HPP and _HPX tables before using the
> information to program registers of PCIe devices. Up until HPX type 2,
> there was only one structure of each type, so we could cheat and store
> it on the stack.
>
> With HPX type 3 we get an arbitrary number of entries, so the above
> model doesn't scale that well. Instead of parsing all tables at once,
> parse and program each entry separately. For _HPP and _HPX 0 thru 2,
> this is functionally equivalent. The change enables the upcoming _HPX3
> to integrate more easily.

I think this is tremendous! It's going to simplify this code
dramatically. Two comments below.

> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> ---
> drivers/pci/pci-acpi.c | 108 +++++++++++++++++++-----------------
> drivers/pci/probe.c | 16 ++----
> include/linux/pci_hotplug.h | 18 +++---
> 3 files changed, 72 insertions(+), 70 deletions(-)
>
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index b25e5fa9d1c9..95f4f86d2f34 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -119,7 +119,7 @@ phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
> }
>
> static acpi_status decode_type0_hpx_record(union acpi_object *record,
> - struct hotplug_params *hpx)
> + struct hpp_type0 *hpx0)
> {
> int i;
> union acpi_object *fields = record->package.elements;
> @@ -132,12 +132,11 @@ static acpi_status decode_type0_hpx_record(union acpi_object *record,
> for (i = 2; i < 6; i++)
> if (fields[i].type != ACPI_TYPE_INTEGER)
> return AE_ERROR;
> - hpx->t0 = &hpx->type0_data;
> - hpx->t0->revision = revision;
> - hpx->t0->cache_line_size = fields[2].integer.value;
> - hpx->t0->latency_timer = fields[3].integer.value;
> - hpx->t0->enable_serr = fields[4].integer.value;
> - hpx->t0->enable_perr = fields[5].integer.value;
> + hpx0->revision = revision;
> + hpx0->cache_line_size = fields[2].integer.value;
> + hpx0->latency_timer = fields[3].integer.value;
> + hpx0->enable_serr = fields[4].integer.value;
> + hpx0->enable_perr = fields[5].integer.value;
> break;
> default:
> printk(KERN_WARNING
> @@ -149,7 +148,7 @@ static acpi_status decode_type0_hpx_record(union acpi_object *record,
> }
>
> static acpi_status decode_type1_hpx_record(union acpi_object *record,
> - struct hotplug_params *hpx)
> + struct hpp_type1 *hpx1)
> {
> int i;
> union acpi_object *fields = record->package.elements;
> @@ -162,11 +161,10 @@ static acpi_status decode_type1_hpx_record(union acpi_object *record,
> for (i = 2; i < 5; i++)
> if (fields[i].type != ACPI_TYPE_INTEGER)
> return AE_ERROR;
> - hpx->t1 = &hpx->type1_data;
> - hpx->t1->revision = revision;
> - hpx->t1->max_mem_read = fields[2].integer.value;
> - hpx->t1->avg_max_split = fields[3].integer.value;
> - hpx->t1->tot_max_split = fields[4].integer.value;
> + hpx1->revision = revision;
> + hpx1->max_mem_read = fields[2].integer.value;
> + hpx1->avg_max_split = fields[3].integer.value;
> + hpx1->tot_max_split = fields[4].integer.value;
> break;
> default:
> printk(KERN_WARNING
> @@ -178,7 +176,7 @@ static acpi_status decode_type1_hpx_record(union acpi_object *record,
> }
>
> static acpi_status decode_type2_hpx_record(union acpi_object *record,
> - struct hotplug_params *hpx)
> + struct hpp_type2 *hpx2)
> {
> int i;
> union acpi_object *fields = record->package.elements;
> @@ -191,24 +189,23 @@ static acpi_status decode_type2_hpx_record(union acpi_object *record,
> for (i = 2; i < 18; i++)
> if (fields[i].type != ACPI_TYPE_INTEGER)
> return AE_ERROR;
> - hpx->t2 = &hpx->type2_data;
> - hpx->t2->revision = revision;
> - hpx->t2->unc_err_mask_and = fields[2].integer.value;
> - hpx->t2->unc_err_mask_or = fields[3].integer.value;
> - hpx->t2->unc_err_sever_and = fields[4].integer.value;
> - hpx->t2->unc_err_sever_or = fields[5].integer.value;
> - hpx->t2->cor_err_mask_and = fields[6].integer.value;
> - hpx->t2->cor_err_mask_or = fields[7].integer.value;
> - hpx->t2->adv_err_cap_and = fields[8].integer.value;
> - hpx->t2->adv_err_cap_or = fields[9].integer.value;
> - hpx->t2->pci_exp_devctl_and = fields[10].integer.value;
> - hpx->t2->pci_exp_devctl_or = fields[11].integer.value;
> - hpx->t2->pci_exp_lnkctl_and = fields[12].integer.value;
> - hpx->t2->pci_exp_lnkctl_or = fields[13].integer.value;
> - hpx->t2->sec_unc_err_sever_and = fields[14].integer.value;
> - hpx->t2->sec_unc_err_sever_or = fields[15].integer.value;
> - hpx->t2->sec_unc_err_mask_and = fields[16].integer.value;
> - hpx->t2->sec_unc_err_mask_or = fields[17].integer.value;
> + hpx2->revision = revision;
> + hpx2->unc_err_mask_and = fields[2].integer.value;
> + hpx2->unc_err_mask_or = fields[3].integer.value;
> + hpx2->unc_err_sever_and = fields[4].integer.value;
> + hpx2->unc_err_sever_or = fields[5].integer.value;
> + hpx2->cor_err_mask_and = fields[6].integer.value;
> + hpx2->cor_err_mask_or = fields[7].integer.value;
> + hpx2->adv_err_cap_and = fields[8].integer.value;
> + hpx2->adv_err_cap_or = fields[9].integer.value;
> + hpx2->pci_exp_devctl_and = fields[10].integer.value;
> + hpx2->pci_exp_devctl_or = fields[11].integer.value;
> + hpx2->pci_exp_lnkctl_and = fields[12].integer.value;
> + hpx2->pci_exp_lnkctl_or = fields[13].integer.value;
> + hpx2->sec_unc_err_sever_and = fields[14].integer.value;
> + hpx2->sec_unc_err_sever_or = fields[15].integer.value;
> + hpx2->sec_unc_err_mask_and = fields[16].integer.value;
> + hpx2->sec_unc_err_mask_or = fields[17].integer.value;
> break;
> default:
> printk(KERN_WARNING
> @@ -219,17 +216,18 @@ static acpi_status decode_type2_hpx_record(union acpi_object *record,
> return AE_OK;
> }
>
> -static acpi_status acpi_run_hpx(acpi_handle handle, struct hotplug_params *hpx)
> +static acpi_status acpi_run_hpx(struct pci_dev *dev, acpi_handle handle,
> + const struct hotplug_program_ops *hp_ops)
> {
> acpi_status status;
> struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
> union acpi_object *package, *record, *fields;
> + struct hpp_type0 hpx0;
> + struct hpp_type1 hpx1;
> + struct hpp_type2 hpx2;
> u32 type;
> int i;
>
> - /* Clear the return buffer with zeros */
> - memset(hpx, 0, sizeof(struct hotplug_params));
> -
> status = acpi_evaluate_object(handle, "_HPX", NULL, &buffer);
> if (ACPI_FAILURE(status))
> return status;
> @@ -257,19 +255,25 @@ static acpi_status acpi_run_hpx(acpi_handle handle, struct hotplug_params *hpx)
> type = fields[0].integer.value;
> switch (type) {
> case 0:
> - status = decode_type0_hpx_record(record, hpx);
> + memset(&hpx0, 0, sizeof(hpx0));
> + status = decode_type0_hpx_record(record, &hpx0);
> if (ACPI_FAILURE(status))
> goto exit;
> + hp_ops->program_type0(dev, &hpx0);
> break;
> case 1:
> - status = decode_type1_hpx_record(record, hpx);
> + memset(&hpx1, 0, sizeof(hpx1));
> + status = decode_type1_hpx_record(record, &hpx1);
> if (ACPI_FAILURE(status))
> goto exit;
> + hp_ops->program_type1(dev, &hpx1);
> break;
> case 2:
> - status = decode_type2_hpx_record(record, hpx);
> + memset(&hpx2, 0, sizeof(hpx2));
> + status = decode_type2_hpx_record(record, &hpx2);
> if (ACPI_FAILURE(status))
> goto exit;
> + hp_ops->program_type2(dev, &hpx2);
> break;
> default:
> printk(KERN_ERR "%s: Type %d record not supported\n",
> @@ -283,14 +287,16 @@ static acpi_status acpi_run_hpx(acpi_handle handle, struct hotplug_params *hpx)
> return status;
> }
>
> -static acpi_status acpi_run_hpp(acpi_handle handle, struct hotplug_params *hpp)
> +static acpi_status acpi_run_hpp(struct pci_dev *dev, acpi_handle handle,
> + const struct hotplug_program_ops *hp_ops)
> {
> acpi_status status;
> struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> union acpi_object *package, *fields;
> + struct hpp_type0 hpp0;
> int i;
>
> - memset(hpp, 0, sizeof(struct hotplug_params));
> + memset(&hpp0, 0, sizeof(hpp0));
>
> status = acpi_evaluate_object(handle, "_HPP", NULL, &buffer);
> if (ACPI_FAILURE(status))
> @@ -311,12 +317,13 @@ static acpi_status acpi_run_hpp(acpi_handle handle, struct hotplug_params *hpp)
> }
> }
>
> - hpp->t0 = &hpp->type0_data;
> - hpp->t0->revision = 1;
> - hpp->t0->cache_line_size = fields[0].integer.value;
> - hpp->t0->latency_timer = fields[1].integer.value;
> - hpp->t0->enable_serr = fields[2].integer.value;
> - hpp->t0->enable_perr = fields[3].integer.value;
> + hpp0.revision = 1;
> + hpp0.cache_line_size = fields[0].integer.value;
> + hpp0.latency_timer = fields[1].integer.value;
> + hpp0.enable_serr = fields[2].integer.value;
> + hpp0.enable_perr = fields[3].integer.value;
> +
> + hp_ops->program_type0(dev, &hpp0);
>
> exit:
> kfree(buffer.pointer);
> @@ -328,7 +335,8 @@ static acpi_status acpi_run_hpp(acpi_handle handle, struct hotplug_params *hpp)
> * @dev - the pci_dev for which we want parameters
> * @hpp - allocated by the caller
> */
> -int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp)
> +int pci_acpi_program_hp_params(struct pci_dev *dev,
> + const struct hotplug_program_ops *hp_ops)
> {
> acpi_status status;
> acpi_handle handle, phandle;
> @@ -351,10 +359,10 @@ int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp)
> * this pci dev.
> */
> while (handle) {
> - status = acpi_run_hpx(handle, hpp);
> + status = acpi_run_hpx(dev, handle, hp_ops);
> if (ACPI_SUCCESS(status))
> return 0;
> - status = acpi_run_hpp(handle, hpp);
> + status = acpi_run_hpp(dev, handle, hp_ops);
> if (ACPI_SUCCESS(status))
> return 0;
> if (acpi_is_root_bridge(handle))
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 257b9f6f2ebb..527c209f0c94 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2131,8 +2131,11 @@ static void pci_configure_eetlp_prefix(struct pci_dev *dev)
>
> static void pci_configure_device(struct pci_dev *dev)
> {
> - struct hotplug_params hpp;
> - int ret;
> + static const struct hotplug_program_ops hp_ops = {
> + .program_type0 = program_hpp_type0,
> + .program_type1 = program_hpp_type1,
> + .program_type2 = program_hpp_type2,
> + };

What if we just moved program_hpp_type0(), etc from probe.c to
pci-acpi.c? The only reason I see to have it in probe.c is for
pci_default_type0, and I think that is a pretty obtuse way of doing
default configuration. I would have no problem at all just hardcoding
those defaults in probe.c and then potentially having them overwritten
by _HPP/_HPX.

If we moved program_hpp_type0(), etc to pci-acpi.c, we could get rid
of the function pointers and all the ACPI-related code would be in one
place.

> pci_configure_mps(dev);
> pci_configure_extended_tags(dev, NULL);
> @@ -2140,14 +2143,7 @@ static void pci_configure_device(struct pci_dev *dev)
> pci_configure_ltr(dev);
> pci_configure_eetlp_prefix(dev);
>
> - memset(&hpp, 0, sizeof(hpp));
> - ret = pci_get_hp_params(dev, &hpp);
> - if (ret)
> - return;
> -
> - program_hpp_type2(dev, hpp.t2);
> - program_hpp_type1(dev, hpp.t1);
> - program_hpp_type0(dev, hpp.t0);
> + pci_acpi_program_hp_params(dev, &hp_ops);
> }
>
> static void pci_release_capabilities(struct pci_dev *dev)
> diff --git a/include/linux/pci_hotplug.h b/include/linux/pci_hotplug.h
> index 7acc9f91e72b..c85378edf235 100644
> --- a/include/linux/pci_hotplug.h
> +++ b/include/linux/pci_hotplug.h
> @@ -124,26 +124,24 @@ struct hpp_type2 {
> u32 sec_unc_err_mask_or;
> };
>
> -struct hotplug_params {
> - struct hpp_type0 *t0; /* Type0: NULL if not available */
> - struct hpp_type1 *t1; /* Type1: NULL if not available */
> - struct hpp_type2 *t2; /* Type2: NULL if not available */
> - struct hpp_type0 type0_data;
> - struct hpp_type1 type1_data;
> - struct hpp_type2 type2_data;
> +struct hotplug_program_ops {
> + void (*program_type0)(struct pci_dev *dev, struct hpp_type0 *hpp);
> + void (*program_type1)(struct pci_dev *dev, struct hpp_type1 *hpp);
> + void (*program_type2)(struct pci_dev *dev, struct hpp_type2 *hpp);
> };

I think a lot of this stuff is only used in drivers/pci, so it could
be moved from include/linux/pci_hotplug.h to drivers/pci/pci.h.

> #ifdef CONFIG_ACPI
> #include <linux/acpi.h>
> -int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp);
> +int pci_acpi_program_hp_params(struct pci_dev *dev,
> + const struct hotplug_program_ops *hp_ops);
> bool pciehp_is_native(struct pci_dev *bridge);
> int acpi_get_hp_hw_control_from_firmware(struct pci_dev *bridge);
> bool shpchp_is_native(struct pci_dev *bridge);
> int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle);
> int acpi_pci_detect_ejectable(acpi_handle handle);
> #else
> -static inline int pci_get_hp_params(struct pci_dev *dev,
> - struct hotplug_params *hpp)
> +int pci_acpi_program_hp_params(struct pci_dev *dev,
> + const struct hotplug_program_ops *hp_ops);
> {
> return -ENODEV;
> }
> --
> 2.19.2
>