* [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-07 21:38 [PATCH v2 0/4] Enable to set DbC strings through sysfs Łukasz Bartosik
@ 2025-10-07 21:38 ` Łukasz Bartosik
2025-10-10 11:09 ` Mathias Nyman
2025-10-07 21:39 ` [PATCH v2 2/4] xhci: dbc: allow to set serial number " Łukasz Bartosik
` (2 subsequent siblings)
3 siblings, 1 reply; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-07 21:38 UTC (permalink / raw)
To: Mathias Nyman, Greg Kroah-Hartman; +Cc: linux-usb, Łukasz Bartosik
From: Łukasz Bartosik <ukaszb@chromium.org>
Reorganize the code to prepare ground for setting serial number,
product and manufacturer names through sysfs. This commit:
1. Introduces new buffers for storing serial number, product and
manufacturer name in utf8. The buffers will be used by sysfs
*_show and *_store functions.
2. Increases USB string descriptor data maximum length to the
value from USB specification (126 bytes of data).
3. Adds new helper functions get_str_desc_len, prepare_len
and xhci_dbc_populate_str_desc.
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
drivers/usb/host/xhci-dbgcap.c | 145 ++++++++++++++++++---------------
drivers/usb/host/xhci-dbgcap.h | 24 ++++--
2 files changed, 94 insertions(+), 75 deletions(-)
diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index 63edf2d8f245..c2fecaffd6f3 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -52,55 +52,6 @@ static void dbc_ring_free(struct device *dev, struct xhci_ring *ring)
kfree(ring);
}
-static u32 xhci_dbc_populate_strings(struct dbc_str_descs *strings)
-{
- struct usb_string_descriptor *s_desc;
- u32 string_length;
-
- /* Serial string: */
- s_desc = (struct usb_string_descriptor *)strings->serial;
- utf8s_to_utf16s(DBC_STRING_SERIAL, strlen(DBC_STRING_SERIAL),
- UTF16_LITTLE_ENDIAN, (wchar_t *)s_desc->wData,
- DBC_MAX_STRING_LENGTH);
-
- s_desc->bLength = (strlen(DBC_STRING_SERIAL) + 1) * 2;
- s_desc->bDescriptorType = USB_DT_STRING;
- string_length = s_desc->bLength;
- string_length <<= 8;
-
- /* Product string: */
- s_desc = (struct usb_string_descriptor *)strings->product;
- utf8s_to_utf16s(DBC_STRING_PRODUCT, strlen(DBC_STRING_PRODUCT),
- UTF16_LITTLE_ENDIAN, (wchar_t *)s_desc->wData,
- DBC_MAX_STRING_LENGTH);
-
- s_desc->bLength = (strlen(DBC_STRING_PRODUCT) + 1) * 2;
- s_desc->bDescriptorType = USB_DT_STRING;
- string_length += s_desc->bLength;
- string_length <<= 8;
-
- /* Manufacture string: */
- s_desc = (struct usb_string_descriptor *)strings->manufacturer;
- utf8s_to_utf16s(DBC_STRING_MANUFACTURER,
- strlen(DBC_STRING_MANUFACTURER),
- UTF16_LITTLE_ENDIAN, (wchar_t *)s_desc->wData,
- DBC_MAX_STRING_LENGTH);
-
- s_desc->bLength = (strlen(DBC_STRING_MANUFACTURER) + 1) * 2;
- s_desc->bDescriptorType = USB_DT_STRING;
- string_length += s_desc->bLength;
- string_length <<= 8;
-
- /* String0: */
- strings->string0[0] = 4;
- strings->string0[1] = USB_DT_STRING;
- strings->string0[2] = 0x09;
- strings->string0[3] = 0x04;
- string_length += 4;
-
- return string_length;
-}
-
static void xhci_dbc_init_ep_contexts(struct xhci_dbc *dbc)
{
struct xhci_ep_ctx *ep_ctx;
@@ -124,7 +75,63 @@ static void xhci_dbc_init_ep_contexts(struct xhci_dbc *dbc)
ep_ctx->deq = cpu_to_le64(deq | dbc->ring_in->cycle_state);
}
-static void xhci_dbc_init_contexts(struct xhci_dbc *dbc, u32 string_length)
+static u8 get_str_desc_len(const char *desc)
+{
+ return ((struct usb_string_descriptor *)desc)->bLength;
+}
+
+static u32 prepare_len(struct dbc_str_descs *descs)
+{
+ u32 len;
+
+ len = get_str_desc_len(descs->serial);
+ len <<= 8;
+ len += get_str_desc_len(descs->product);
+ len <<= 8;
+ len += get_str_desc_len(descs->manufacturer);
+ len <<= 8;
+ len += get_str_desc_len(descs->string0);
+
+ return len;
+}
+
+static int xhci_dbc_populate_str_desc(char *desc, const char *src)
+{
+ struct usb_string_descriptor *s_desc;
+ int utf16_len;
+
+ s_desc = (struct usb_string_descriptor *)desc;
+ utf16_len = utf8s_to_utf16s(src, strlen(src), UTF16_LITTLE_ENDIAN,
+ (wchar_t *)s_desc->wData, USB_MAX_STRING_LEN);
+ if (utf16_len < 0)
+ return utf16_len;
+
+ s_desc->bLength = utf16_len * 2 + 2;
+ s_desc->bDescriptorType = USB_DT_STRING;
+
+ return s_desc->bLength;
+}
+
+static void xhci_dbc_populate_str_descs(struct dbc_str_descs *str_descs,
+ struct dbc_str *str)
+{
+ /* Serial string: */
+ xhci_dbc_populate_str_desc(str_descs->serial, str->serial);
+
+ /* Product string: */
+ xhci_dbc_populate_str_desc(str_descs->product, str->product);
+
+ /* Manufacturer string: */
+ xhci_dbc_populate_str_desc(str_descs->manufacturer, str->manufacturer);
+
+ /* String0: */
+ str_descs->string0[0] = 4;
+ str_descs->string0[1] = USB_DT_STRING;
+ str_descs->string0[2] = 0x09;
+ str_descs->string0[3] = 0x04;
+}
+
+static void xhci_dbc_init_contexts(struct xhci_dbc *dbc)
{
struct dbc_info_context *info;
u32 dev_info;
@@ -135,12 +142,12 @@ static void xhci_dbc_init_contexts(struct xhci_dbc *dbc, u32 string_length)
/* Populate info Context: */
info = (struct dbc_info_context *)dbc->ctx->bytes;
- dma = dbc->string_dma;
+ dma = dbc->str_descs_dma;
info->string0 = cpu_to_le64(dma);
- info->manufacturer = cpu_to_le64(dma + DBC_MAX_STRING_LENGTH);
- info->product = cpu_to_le64(dma + DBC_MAX_STRING_LENGTH * 2);
- info->serial = cpu_to_le64(dma + DBC_MAX_STRING_LENGTH * 3);
- info->length = cpu_to_le32(string_length);
+ info->manufacturer = cpu_to_le64(dma + USB_MAX_STRING_DESC_LEN);
+ info->product = cpu_to_le64(dma + USB_MAX_STRING_DESC_LEN*2);
+ info->serial = cpu_to_le64(dma + USB_MAX_STRING_DESC_LEN*3);
+ info->length = cpu_to_le32(prepare_len(dbc->str_descs));
/* Populate bulk in and out endpoint contexts: */
xhci_dbc_init_ep_contexts(dbc);
@@ -525,7 +532,6 @@ static int xhci_dbc_mem_init(struct xhci_dbc *dbc, gfp_t flags)
{
int ret;
dma_addr_t deq;
- u32 string_length;
struct device *dev = dbc->dev;
/* Allocate various rings for events and transfers: */
@@ -552,11 +558,11 @@ static int xhci_dbc_mem_init(struct xhci_dbc *dbc, gfp_t flags)
goto ctx_fail;
/* Allocate the string table: */
- dbc->string_size = sizeof(*dbc->string);
- dbc->string = dma_alloc_coherent(dev, dbc->string_size,
- &dbc->string_dma, flags);
- if (!dbc->string)
- goto string_fail;
+ dbc->str_descs_size = sizeof(*dbc->str_descs);
+ dbc->str_descs = dma_alloc_coherent(dev, dbc->str_descs_size,
+ &dbc->str_descs_dma, flags);
+ if (!dbc->str_descs)
+ goto str_descs_fail;
/* Setup ERST register: */
writel(dbc->erst.num_entries, &dbc->regs->ersts);
@@ -566,16 +572,16 @@ static int xhci_dbc_mem_init(struct xhci_dbc *dbc, gfp_t flags)
dbc->ring_evt->dequeue);
lo_hi_writeq(deq, &dbc->regs->erdp);
- /* Setup strings and contexts: */
- string_length = xhci_dbc_populate_strings(dbc->string);
- xhci_dbc_init_contexts(dbc, string_length);
+ /* Setup string descriptors and contexts: */
+ xhci_dbc_populate_str_descs(dbc->str_descs, &dbc->str);
+ xhci_dbc_init_contexts(dbc);
xhci_dbc_eps_init(dbc);
dbc->state = DS_INITIALIZED;
return 0;
-string_fail:
+str_descs_fail:
dbc_free_ctx(dev, dbc->ctx);
dbc->ctx = NULL;
ctx_fail:
@@ -600,8 +606,8 @@ static void xhci_dbc_mem_cleanup(struct xhci_dbc *dbc)
xhci_dbc_eps_exit(dbc);
- dma_free_coherent(dbc->dev, dbc->string_size, dbc->string, dbc->string_dma);
- dbc->string = NULL;
+ dma_free_coherent(dbc->dev, dbc->str_descs_size, dbc->str_descs, dbc->str_descs_dma);
+ dbc->str_descs = NULL;
dbc_free_ctx(dbc->dev, dbc->ctx);
dbc->ctx = NULL;
@@ -1314,6 +1320,11 @@ xhci_alloc_dbc(struct device *dev, void __iomem *base, const struct dbc_driver *
dbc->bInterfaceProtocol = DBC_PROTOCOL;
dbc->poll_interval = DBC_POLL_INTERVAL_DEFAULT;
+ /* initialize serial, product and manufacturer with default values */
+ memcpy(dbc->str.serial, DBC_STRING_SERIAL, strlen(DBC_STRING_SERIAL)+1);
+ memcpy(dbc->str.product, DBC_STRING_PRODUCT, strlen(DBC_STRING_PRODUCT)+1);
+ memcpy(dbc->str.manufacturer, DBC_STRING_MANUFACTURER, strlen(DBC_STRING_MANUFACTURER)+1);
+
if (readl(&dbc->regs->control) & DBC_CTRL_DBC_ENABLE)
goto err;
diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h
index 47ac72c2286d..0e6addafea6c 100644
--- a/drivers/usb/host/xhci-dbgcap.h
+++ b/drivers/usb/host/xhci-dbgcap.h
@@ -47,7 +47,6 @@ struct dbc_info_context {
#define DBC_DOOR_BELL_TARGET(p) (((p) & 0xff) << 8)
#define DBC_MAX_PACKET 1024
-#define DBC_MAX_STRING_LENGTH 64
#define DBC_STRING_MANUFACTURER "Linux Foundation"
#define DBC_STRING_PRODUCT "Linux USB Debug Target"
#define DBC_STRING_SERIAL "0001"
@@ -63,11 +62,19 @@ struct dbc_info_context {
#define DBC_PORTSC_LINK_CHANGE BIT(22)
#define DBC_PORTSC_CONFIG_CHANGE BIT(23)
+#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN + 2)
+
struct dbc_str_descs {
- char string0[DBC_MAX_STRING_LENGTH];
- char manufacturer[DBC_MAX_STRING_LENGTH];
- char product[DBC_MAX_STRING_LENGTH];
- char serial[DBC_MAX_STRING_LENGTH];
+ char string0[USB_MAX_STRING_DESC_LEN];
+ char manufacturer[USB_MAX_STRING_DESC_LEN];
+ char product[USB_MAX_STRING_DESC_LEN];
+ char serial[USB_MAX_STRING_DESC_LEN];
+};
+
+struct dbc_str {
+ char manufacturer[USB_MAX_STRING_LEN/2+1];
+ char product[USB_MAX_STRING_LEN/2+1];
+ char serial[USB_MAX_STRING_LEN/2+1];
};
#define DBC_PROTOCOL 1 /* GNU Remote Debug Command */
@@ -132,9 +139,10 @@ struct xhci_dbc {
struct xhci_erst erst;
struct xhci_container_ctx *ctx;
- struct dbc_str_descs *string;
- dma_addr_t string_dma;
- size_t string_size;
+ struct dbc_str_descs *str_descs;
+ dma_addr_t str_descs_dma;
+ size_t str_descs_size;
+ struct dbc_str str;
u16 idVendor;
u16 idProduct;
u16 bcdDevice;
--
2.51.0.710.ga91ca5db03-goog
^ permalink raw reply related [flat|nested] 16+ messages in thread* Re: [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-07 21:38 ` [PATCH v2 1/4] xhci: dbc: prepare to expose " Łukasz Bartosik
@ 2025-10-10 11:09 ` Mathias Nyman
2025-10-11 11:22 ` Łukasz Bartosik
0 siblings, 1 reply; 16+ messages in thread
From: Mathias Nyman @ 2025-10-10 11:09 UTC (permalink / raw)
To: Łukasz Bartosik, Mathias Nyman, Greg Kroah-Hartman,
Łukasz Bartosik, Mathias Nyman, Greg Kroah-Hartman
Cc: linux-usb
On 10/8/25 00:38, Łukasz Bartosik wrote:
> From: Łukasz Bartosik <ukaszb@chromium.org>
>
> Reorganize the code to prepare ground for setting serial number,
> product and manufacturer names through sysfs. This commit:
> 1. Introduces new buffers for storing serial number, product and
> manufacturer name in utf8. The buffers will be used by sysfs
> *_show and *_store functions.
> 2. Increases USB string descriptor data maximum length to the
> value from USB specification (126 bytes of data).
> 3. Adds new helper functions get_str_desc_len, prepare_len
> and xhci_dbc_populate_str_desc.
>
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
This change does in general look good to me.
It gets rid of the code duplication in current xhci_dbc_populate_strings(),
and retains new strings over suspend/resume.
I mostly have minor nitpicks regarding naming and other subjective matters
> ---
> drivers/usb/host/xhci-dbgcap.c | 145 ++++++++++++++++++---------------
> drivers/usb/host/xhci-dbgcap.h | 24 ++++--
> 2 files changed, 94 insertions(+), 75 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> index 63edf2d8f245..c2fecaffd6f3 100644
> --- a/drivers/usb/host/xhci-dbgcap.c
> +++ b/drivers/usb/host/xhci-dbgcap.c
> @@ -124,7 +75,63 @@ static void xhci_dbc_init_ep_contexts(struct xhci_dbc *dbc)
> ep_ctx->deq = cpu_to_le64(deq | dbc->ring_in->cycle_state);
> }
>
> -static void xhci_dbc_init_contexts(struct xhci_dbc *dbc, u32 string_length)
> +static u8 get_str_desc_len(const char *desc)
> +{
> + return ((struct usb_string_descriptor *)desc)->bLength;
> +}
> +
> +static u32 prepare_len(struct dbc_str_descs *descs)
prepare_len() is very generic, how about something like
dbc_prepare_info_context_str_len()
> +{
> + u32 len;
> +
> + len = get_str_desc_len(descs->serial);
> + len <<= 8;
> + len += get_str_desc_len(descs->product);
> + len <<= 8;
> + len += get_str_desc_len(descs->manufacturer);
> + len <<= 8;
> + len += get_str_desc_len(descs->string0);
> +
> + return len;
> +}
> +
> +static int xhci_dbc_populate_str_desc(char *desc, const char *src)
> +{
> + struct usb_string_descriptor *s_desc;
> + int utf16_len;
> +
> + s_desc = (struct usb_string_descriptor *)desc;
> + utf16_len = utf8s_to_utf16s(src, strlen(src), UTF16_LITTLE_ENDIAN,
> + (wchar_t *)s_desc->wData, USB_MAX_STRING_LEN);
The "utf16_len" got me confused.
It's not wrong, but I first assumed it is bytes this utf16 formatted text
takes, when it turns out to be number of u16 entries in the text.
> + if (utf16_len < 0)
> + return utf16_len;
> +
> + s_desc->bLength = utf16_len * 2 + 2;
> + s_desc->bDescriptorType = USB_DT_STRING;
> +
> + return s_desc->bLength;
> +}
> +
> +static void xhci_dbc_populate_str_descs(struct dbc_str_descs *str_descs,
> + struct dbc_str *str)
> +{
> + /* Serial string: */
> + xhci_dbc_populate_str_desc(str_descs->serial, str->serial);
> +
> + /* Product string: */
> + xhci_dbc_populate_str_desc(str_descs->product, str->product);
> +
> + /* Manufacturer string: */
> + xhci_dbc_populate_str_desc(str_descs->manufacturer, str->manufacturer);
> +
> + /* String0: */
> + str_descs->string0[0] = 4;
> + str_descs->string0[1] = USB_DT_STRING;
> + str_descs->string0[2] = 0x09;
> + str_descs->string0[3] = 0x04;
> +}
> @@ -1314,6 +1320,11 @@ xhci_alloc_dbc(struct device *dev, void __iomem *base, const struct dbc_driver *
> dbc->bInterfaceProtocol = DBC_PROTOCOL;
> dbc->poll_interval = DBC_POLL_INTERVAL_DEFAULT;
>
> + /* initialize serial, product and manufacturer with default values */
> + memcpy(dbc->str.serial, DBC_STRING_SERIAL, strlen(DBC_STRING_SERIAL)+1);
> + memcpy(dbc->str.product, DBC_STRING_PRODUCT, strlen(DBC_STRING_PRODUCT)+1);
> + memcpy(dbc->str.manufacturer, DBC_STRING_MANUFACTURER, strlen(DBC_STRING_MANUFACTURER)+1);
> +
Maybe it would be cleaner to just define a default struct for the strings and assign it here.
We could get rid of the #define DBC_STRING_* from the header as well.
i.e.:
static const struct dbc_str dbc_str_default = {
.manufacturer = "Linux Foundation",
.product = "Linux USB Debug Target",
.serial = "0001",
};
xhci_alloc_dbc(..)
{
...
/* initialize serial, product and manufacturer with default values */
dbc->str = dbc_str_default;
}> if (readl(&dbc->regs->control) & DBC_CTRL_DBC_ENABLE)
> goto err;
>
> diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h
> index 47ac72c2286d..0e6addafea6c 100644
> --- a/drivers/usb/host/xhci-dbgcap.h
> +++ b/drivers/usb/host/xhci-dbgcap.h
> @@ -47,7 +47,6 @@ struct dbc_info_context {
> #define DBC_DOOR_BELL_TARGET(p) (((p) & 0xff) << 8)
>
> #define DBC_MAX_PACKET 1024
> -#define DBC_MAX_STRING_LENGTH 64
> #define DBC_STRING_MANUFACTURER "Linux Foundation"
> #define DBC_STRING_PRODUCT "Linux USB Debug Target"
> #define DBC_STRING_SERIAL "0001"
> @@ -63,11 +62,19 @@ struct dbc_info_context {
> #define DBC_PORTSC_LINK_CHANGE BIT(22)
> #define DBC_PORTSC_CONFIG_CHANGE BIT(23)
>
> +#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN + 2)
This looks like somthing that would be defined in ch9.h or usb.h.
Maybe a more local name like DBC_MAX_STRING_DESC_LEN
> +
> struct dbc_str_descs {
> - char string0[DBC_MAX_STRING_LENGTH];
> - char manufacturer[DBC_MAX_STRING_LENGTH];
> - char product[DBC_MAX_STRING_LENGTH];
> - char serial[DBC_MAX_STRING_LENGTH];
> + char string0[USB_MAX_STRING_DESC_LEN];
> + char manufacturer[USB_MAX_STRING_DESC_LEN];
> + char product[USB_MAX_STRING_DESC_LEN];
> + char serial[USB_MAX_STRING_DESC_LEN];
> +};
> +
> +struct dbc_str {> + char manufacturer[USB_MAX_STRING_LEN/2+1];
> + char product[USB_MAX_STRING_LEN/2+1];
> + char serial[USB_MAX_STRING_LEN/2+1];
> };
Maybe some comment above to clarify the odd size
/* utf8 strings used to create the USB_MAX_STRING_LEN utf16 string descriptors */
Thanks
Mathias
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-10 11:09 ` Mathias Nyman
@ 2025-10-11 11:22 ` Łukasz Bartosik
2025-10-11 17:13 ` Alan Stern
2025-10-13 8:18 ` Mathias Nyman
0 siblings, 2 replies; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-11 11:22 UTC (permalink / raw)
To: Mathias Nyman; +Cc: Greg Kroah-Hartman, linux-usb
On Fri, Oct 10, 2025 at 1:09 PM Mathias Nyman <mathias.nyman@intel.com> wrote:
>
> On 10/8/25 00:38, Łukasz Bartosik wrote:
> > From: Łukasz Bartosik <ukaszb@chromium.org>
> >
> > Reorganize the code to prepare ground for setting serial number,
> > product and manufacturer names through sysfs. This commit:
> > 1. Introduces new buffers for storing serial number, product and
> > manufacturer name in utf8. The buffers will be used by sysfs
> > *_show and *_store functions.
> > 2. Increases USB string descriptor data maximum length to the
> > value from USB specification (126 bytes of data).
> > 3. Adds new helper functions get_str_desc_len, prepare_len
> > and xhci_dbc_populate_str_desc.
> >
> > Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
>
> This change does in general look good to me.
>
> It gets rid of the code duplication in current xhci_dbc_populate_strings(),
> and retains new strings over suspend/resume.
>
> I mostly have minor nitpicks regarding naming and other subjective matters
>
Thank you Mathias for the review.
> > ---
> > drivers/usb/host/xhci-dbgcap.c | 145 ++++++++++++++++++---------------
> > drivers/usb/host/xhci-dbgcap.h | 24 ++++--
> > 2 files changed, 94 insertions(+), 75 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> > index 63edf2d8f245..c2fecaffd6f3 100644
> > --- a/drivers/usb/host/xhci-dbgcap.c
> > +++ b/drivers/usb/host/xhci-dbgcap.c
> > @@ -124,7 +75,63 @@ static void xhci_dbc_init_ep_contexts(struct xhci_dbc *dbc)
> > ep_ctx->deq = cpu_to_le64(deq | dbc->ring_in->cycle_state);
> > }
> >
> > -static void xhci_dbc_init_contexts(struct xhci_dbc *dbc, u32 string_length)
> > +static u8 get_str_desc_len(const char *desc)
> > +{
> > + return ((struct usb_string_descriptor *)desc)->bLength;
> > +}
> > +
> > +static u32 prepare_len(struct dbc_str_descs *descs)
>
> prepare_len() is very generic, how about something like
>
> dbc_prepare_info_context_str_len()
>
I will change it in patchset v3.
> > +{
> > + u32 len;
> > +
> > + len = get_str_desc_len(descs->serial);
> > + len <<= 8;
> > + len += get_str_desc_len(descs->product);
> > + len <<= 8;
> > + len += get_str_desc_len(descs->manufacturer);
> > + len <<= 8;
> > + len += get_str_desc_len(descs->string0);
> > +
> > + return len;
> > +}
> > +
> > +static int xhci_dbc_populate_str_desc(char *desc, const char *src)
> > +{
> > + struct usb_string_descriptor *s_desc;
> > + int utf16_len;
> > +
> > + s_desc = (struct usb_string_descriptor *)desc;
> > + utf16_len = utf8s_to_utf16s(src, strlen(src), UTF16_LITTLE_ENDIAN,
> > + (wchar_t *)s_desc->wData, USB_MAX_STRING_LEN);
>
> The "utf16_len" got me confused.
> It's not wrong, but I first assumed it is bytes this utf16 formatted text
> takes, when it turns out to be number of u16 entries in the text.
>
Do you have a suggestion how to rename it to be more self commenting ?
Or maybe I will rename it to len and add a comment that it holds a number
of u16 entries ? WDYT ?
> > + if (utf16_len < 0)
> > + return utf16_len;
> > +
> > + s_desc->bLength = utf16_len * 2 + 2;
> > + s_desc->bDescriptorType = USB_DT_STRING;
> > +
> > + return s_desc->bLength;
> > +}
> > +
> > +static void xhci_dbc_populate_str_descs(struct dbc_str_descs *str_descs,
> > + struct dbc_str *str)
> > +{
> > + /* Serial string: */
> > + xhci_dbc_populate_str_desc(str_descs->serial, str->serial);
> > +
> > + /* Product string: */
> > + xhci_dbc_populate_str_desc(str_descs->product, str->product);
> > +
> > + /* Manufacturer string: */
> > + xhci_dbc_populate_str_desc(str_descs->manufacturer, str->manufacturer);
> > +
> > + /* String0: */
> > + str_descs->string0[0] = 4;
> > + str_descs->string0[1] = USB_DT_STRING;
> > + str_descs->string0[2] = 0x09;
> > + str_descs->string0[3] = 0x04;
> > +}
>
> > @@ -1314,6 +1320,11 @@ xhci_alloc_dbc(struct device *dev, void __iomem *base, const struct dbc_driver *
> > dbc->bInterfaceProtocol = DBC_PROTOCOL;
> > dbc->poll_interval = DBC_POLL_INTERVAL_DEFAULT;
> >
> > + /* initialize serial, product and manufacturer with default values */
> > + memcpy(dbc->str.serial, DBC_STRING_SERIAL, strlen(DBC_STRING_SERIAL)+1);
> > + memcpy(dbc->str.product, DBC_STRING_PRODUCT, strlen(DBC_STRING_PRODUCT)+1);
> > + memcpy(dbc->str.manufacturer, DBC_STRING_MANUFACTURER, strlen(DBC_STRING_MANUFACTURER)+1);
> > +
>
> Maybe it would be cleaner to just define a default struct for the strings and assign it here.
> We could get rid of the #define DBC_STRING_* from the header as well.
>
> i.e.:
>
> static const struct dbc_str dbc_str_default = {
> .manufacturer = "Linux Foundation",
> .product = "Linux USB Debug Target",
> .serial = "0001",
> };
>
> xhci_alloc_dbc(..)
> {
> ...
> /* initialize serial, product and manufacturer with default values */
> dbc->str = dbc_str_default;
Neat ;). I will change it in patchset v3.
> }> if (readl(&dbc->regs->control) & DBC_CTRL_DBC_ENABLE)
> > goto err;
> >
> > diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h
> > index 47ac72c2286d..0e6addafea6c 100644
> > --- a/drivers/usb/host/xhci-dbgcap.h
> > +++ b/drivers/usb/host/xhci-dbgcap.h
> > @@ -47,7 +47,6 @@ struct dbc_info_context {
> > #define DBC_DOOR_BELL_TARGET(p) (((p) & 0xff) << 8)
> >
> > #define DBC_MAX_PACKET 1024
> > -#define DBC_MAX_STRING_LENGTH 64
> > #define DBC_STRING_MANUFACTURER "Linux Foundation"
> > #define DBC_STRING_PRODUCT "Linux USB Debug Target"
> > #define DBC_STRING_SERIAL "0001"
> > @@ -63,11 +62,19 @@ struct dbc_info_context {
> > #define DBC_PORTSC_LINK_CHANGE BIT(22)
> > #define DBC_PORTSC_CONFIG_CHANGE BIT(23)
> >
> > +#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN + 2)
>
> This looks like somthing that would be defined in ch9.h or usb.h.
>
Unfortunately I can see only USB_MAX_STRING_LEN but no definition
for a maximum USB string descriptor size.
> Maybe a more local name like DBC_MAX_STRING_DESC_LEN
>
I will rename it and also remove magic number:
#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN +
sizeof(struct usb_string_descriptor))
>
> > +
> > struct dbc_str_descs {
> > - char string0[DBC_MAX_STRING_LENGTH];
> > - char manufacturer[DBC_MAX_STRING_LENGTH];
> > - char product[DBC_MAX_STRING_LENGTH];
> > - char serial[DBC_MAX_STRING_LENGTH];
> > + char string0[USB_MAX_STRING_DESC_LEN];
> > + char manufacturer[USB_MAX_STRING_DESC_LEN];
> > + char product[USB_MAX_STRING_DESC_LEN];
> > + char serial[USB_MAX_STRING_DESC_LEN];
> > +};
> > +
> > +struct dbc_str {> + char manufacturer[USB_MAX_STRING_LEN/2+1];
> > + char product[USB_MAX_STRING_LEN/2+1];
> > + char serial[USB_MAX_STRING_LEN/2+1];
> > };
>
> Maybe some comment above to clarify the odd size
>
> /* utf8 strings used to create the USB_MAX_STRING_LEN utf16 string descriptors */
>
I will add the comment in the patchset v3.
Thanks,
Łukasz
> Thanks
> Mathias
>
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-11 11:22 ` Łukasz Bartosik
@ 2025-10-11 17:13 ` Alan Stern
2025-10-12 15:57 ` Łukasz Bartosik
2025-10-13 8:18 ` Mathias Nyman
1 sibling, 1 reply; 16+ messages in thread
From: Alan Stern @ 2025-10-11 17:13 UTC (permalink / raw)
To: Łukasz Bartosik; +Cc: Mathias Nyman, Greg Kroah-Hartman, linux-usb
On Sat, Oct 11, 2025 at 01:22:45PM +0200, Łukasz Bartosik wrote:
> > > @@ -63,11 +62,19 @@ struct dbc_info_context {
> > > #define DBC_PORTSC_LINK_CHANGE BIT(22)
> > > #define DBC_PORTSC_CONFIG_CHANGE BIT(23)
> > >
> > > +#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN + 2)
> >
> > This looks like somthing that would be defined in ch9.h or usb.h.
> >
>
> Unfortunately I can see only USB_MAX_STRING_LEN but no definition
> for a maximum USB string descriptor size.
The maximum length of a string descriptor is 255, because the bLength
field in the descriptor is __u8. In practice the maximum length is 254,
because a string descriptor consists of a 2-byte header followed by a
bunch of UTF-16LE characters (so 2 bytes each). This allows for only
126 characters (or rather, code points) max in the string, which is
where USB_MAX_STRING_LEN comes from.
> > Maybe a more local name like DBC_MAX_STRING_DESC_LEN
> >
>
> I will rename it and also remove magic number:
> #define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN +
> sizeof(struct usb_string_descriptor))
You might as well just set this to 254.
Alan Stern
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-11 17:13 ` Alan Stern
@ 2025-10-12 15:57 ` Łukasz Bartosik
2025-10-13 8:12 ` Mathias Nyman
0 siblings, 1 reply; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-12 15:57 UTC (permalink / raw)
To: Alan Stern, Mathias Nyman; +Cc: Greg Kroah-Hartman, linux-usb
On Sat, Oct 11, 2025 at 7:13 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>
> On Sat, Oct 11, 2025 at 01:22:45PM +0200, Łukasz Bartosik wrote:
> > > > @@ -63,11 +62,19 @@ struct dbc_info_context {
> > > > #define DBC_PORTSC_LINK_CHANGE BIT(22)
> > > > #define DBC_PORTSC_CONFIG_CHANGE BIT(23)
> > > >
> > > > +#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN + 2)
> > >
> > > This looks like somthing that would be defined in ch9.h or usb.h.
> > >
> >
> > Unfortunately I can see only USB_MAX_STRING_LEN but no definition
> > for a maximum USB string descriptor size.
>
> The maximum length of a string descriptor is 255, because the bLength
> field in the descriptor is __u8. In practice the maximum length is 254,
> because a string descriptor consists of a 2-byte header followed by a
> bunch of UTF-16LE characters (so 2 bytes each). This allows for only
> 126 characters (or rather, code points) max in the string, which is
> where USB_MAX_STRING_LEN comes from.
>
Thank you Alan for pointing out USB_MAX_STRING_LEN is maximum length
in utf16 code points ;).
> > > Maybe a more local name like DBC_MAX_STRING_DESC_LEN
> > >
> >
> > I will rename it and also remove magic number:
> > #define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN +
> > sizeof(struct usb_string_descriptor))
>
> You might as well just set this to 254.
>
Mathias, do you have a preference here?
I mean whether to use
#define USB_MAX_STRING_DESC_LEN 254
or
#define USB_MAX_STRING_DESC_LEN (2*USB_MAX_STRING_LEN +
sizeof(struct usb_string_descriptor))
No matter which one is chosen I will add a comment with Alan's explanation.
Thanks,
Łukasz
> Alan Stern
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-12 15:57 ` Łukasz Bartosik
@ 2025-10-13 8:12 ` Mathias Nyman
0 siblings, 0 replies; 16+ messages in thread
From: Mathias Nyman @ 2025-10-13 8:12 UTC (permalink / raw)
To: Łukasz Bartosik, Alan Stern, Mathias Nyman
Cc: Greg Kroah-Hartman, linux-usb
On 10/12/25 18:57, Łukasz Bartosik wrote:
> On Sat, Oct 11, 2025 at 7:13 PM Alan Stern <stern@rowland.harvard.edu> wrote:
>>
>> On Sat, Oct 11, 2025 at 01:22:45PM +0200, Łukasz Bartosik wrote:
>>>>> @@ -63,11 +62,19 @@ struct dbc_info_context {
>>>>> #define DBC_PORTSC_LINK_CHANGE BIT(22)
>>>>> #define DBC_PORTSC_CONFIG_CHANGE BIT(23)
>>>>>
>>>>> +#define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN + 2)
>>>>
>>>> This looks like somthing that would be defined in ch9.h or usb.h.
>>>>
>>>
>>> Unfortunately I can see only USB_MAX_STRING_LEN but no definition
>>> for a maximum USB string descriptor size.
>>
>> The maximum length of a string descriptor is 255, because the bLength
>> field in the descriptor is __u8. In practice the maximum length is 254,
>> because a string descriptor consists of a 2-byte header followed by a
>> bunch of UTF-16LE characters (so 2 bytes each). This allows for only
>> 126 characters (or rather, code points) max in the string, which is
>> where USB_MAX_STRING_LEN comes from.
>>
>
> Thank you Alan for pointing out USB_MAX_STRING_LEN is maximum length
> in utf16 code points ;).
>
>>>> Maybe a more local name like DBC_MAX_STRING_DESC_LEN
>>>>
>>>
>>> I will rename it and also remove magic number:
>>> #define USB_MAX_STRING_DESC_LEN (USB_MAX_STRING_LEN +
>>> sizeof(struct usb_string_descriptor))
>>
>> You might as well just set this to 254.
>>
>
> Mathias, do you have a preference here?
> I mean whether to use
> #define USB_MAX_STRING_DESC_LEN 254
> or
> #define USB_MAX_STRING_DESC_LEN (2*USB_MAX_STRING_LEN +
> sizeof(struct usb_string_descriptor))
>
> No matter which one is chosen I will add a comment with Alan's explanation.
Setting it to 254 with a comment based on Alan's explanations sounds good to me.
Thanks
Mathias
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 1/4] xhci: dbc: prepare to expose strings through sysfs
2025-10-11 11:22 ` Łukasz Bartosik
2025-10-11 17:13 ` Alan Stern
@ 2025-10-13 8:18 ` Mathias Nyman
1 sibling, 0 replies; 16+ messages in thread
From: Mathias Nyman @ 2025-10-13 8:18 UTC (permalink / raw)
To: Łukasz Bartosik, Mathias Nyman; +Cc: Greg Kroah-Hartman, linux-usb
On 10/11/25 14:22, Łukasz Bartosik wrote:
> On Fri, Oct 10, 2025 at 1:09 PM Mathias Nyman <mathias.nyman@intel.com> wrote:
>>
>> On 10/8/25 00:38, Łukasz Bartosik wrote:
>>> From: Łukasz Bartosik <ukaszb@chromium.org>
>>>
>>> +static int xhci_dbc_populate_str_desc(char *desc, const char *src)
>>> +{
>>> + struct usb_string_descriptor *s_desc;
>>> + int utf16_len;
>>> +
>>> + s_desc = (struct usb_string_descriptor *)desc;
>>> + utf16_len = utf8s_to_utf16s(src, strlen(src), UTF16_LITTLE_ENDIAN,
>>> + (wchar_t *)s_desc->wData, USB_MAX_STRING_LEN);
>>
>> The "utf16_len" got me confused.
>> It's not wrong, but I first assumed it is bytes this utf16 formatted text
>> takes, when it turns out to be number of u16 entries in the text.
>>
>
> Do you have a suggestion how to rename it to be more self commenting ?
> Or maybe I will rename it to len and add a comment that it holds a number
> of u16 entries ? WDYT ?
I don't have a good suggestion. Naming is hard.
'len' with a comment sounds good.
Thanks
Mathias
^ permalink raw reply [flat|nested] 16+ messages in thread
* [PATCH v2 2/4] xhci: dbc: allow to set serial number through sysfs
2025-10-07 21:38 [PATCH v2 0/4] Enable to set DbC strings through sysfs Łukasz Bartosik
2025-10-07 21:38 ` [PATCH v2 1/4] xhci: dbc: prepare to expose " Łukasz Bartosik
@ 2025-10-07 21:39 ` Łukasz Bartosik
2025-10-08 11:20 ` Greg Kroah-Hartman
2025-10-07 21:39 ` [PATCH v2 3/4] xhci: dbc: allow to set product name " Łukasz Bartosik
2025-10-07 21:39 ` [PATCH v2 4/4] xhci: dbc: allow to set manufacturer " Łukasz Bartosik
3 siblings, 1 reply; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-07 21:39 UTC (permalink / raw)
To: Mathias Nyman, Greg Kroah-Hartman; +Cc: linux-usb, Łukasz Bartosik
From: Łukasz Bartosik <ukaszb@chromium.org>
Add code which allows to set serial number of a DbC
device through sysfs.
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
.../testing/sysfs-bus-pci-drivers-xhci_hcd | 13 +++++++
drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
index fc82aa4e54b0..071688dbd969 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -85,3 +85,16 @@ Description:
up to 5000. The default value is 64 ms.
This polling interval is used while DbC is enabled but has no
active data transfers.
+
+What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iSerial
+Date: October 2025
+Contact: Łukasz Bartosik <ukaszb@chromium.org>
+Description:
+ The dbc_iSerial attribute allows to change the iSerial field
+ presented in the USB device descriptor by xhci debug device.
+ Value can only be changed while debug capability (DbC) is in
+ disabled state to prevent USB device descriptor change while
+ connected to a USB host.
+ The default value is "0001".
+ The field length can be from 1 to 63 characters.
+
diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index c2fecaffd6f3..7ad83548ba4d 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
return size;
}
+static ssize_t dbc_iSerial_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+ struct xhci_dbc *dbc = xhci->dbc;
+
+ return sysfs_emit(buf, "%s\n", dbc->str.serial);
+}
+
+static ssize_t dbc_iSerial_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+ struct xhci_dbc *dbc = xhci->dbc;
+ size_t len;
+
+ if (dbc->state != DS_DISABLED)
+ return -EBUSY;
+
+ len = strcspn(buf, "\n");
+ if (!len)
+ return -EINVAL;
+
+ if (len > USB_MAX_STRING_LEN/2)
+ return -E2BIG;
+
+ memcpy(dbc->str.serial, buf, len);
+ dbc->str.serial[len] = '\0';
+
+ return size;
+}
+
static ssize_t dbc_bInterfaceProtocol_show(struct device *dev,
struct device_attribute *attr,
char *buf)
@@ -1287,6 +1321,7 @@ static DEVICE_ATTR_RW(dbc);
static DEVICE_ATTR_RW(dbc_idVendor);
static DEVICE_ATTR_RW(dbc_idProduct);
static DEVICE_ATTR_RW(dbc_bcdDevice);
+static DEVICE_ATTR_RW(dbc_iSerial);
static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
static DEVICE_ATTR_RW(dbc_poll_interval_ms);
@@ -1295,6 +1330,7 @@ static struct attribute *dbc_dev_attrs[] = {
&dev_attr_dbc_idVendor.attr,
&dev_attr_dbc_idProduct.attr,
&dev_attr_dbc_bcdDevice.attr,
+ &dev_attr_dbc_iSerial.attr,
&dev_attr_dbc_bInterfaceProtocol.attr,
&dev_attr_dbc_poll_interval_ms.attr,
NULL
--
2.51.0.710.ga91ca5db03-goog
^ permalink raw reply related [flat|nested] 16+ messages in thread* Re: [PATCH v2 2/4] xhci: dbc: allow to set serial number through sysfs
2025-10-07 21:39 ` [PATCH v2 2/4] xhci: dbc: allow to set serial number " Łukasz Bartosik
@ 2025-10-08 11:20 ` Greg Kroah-Hartman
2025-10-08 21:14 ` Łukasz Bartosik
0 siblings, 1 reply; 16+ messages in thread
From: Greg Kroah-Hartman @ 2025-10-08 11:20 UTC (permalink / raw)
To: Łukasz Bartosik; +Cc: Mathias Nyman, linux-usb
On Tue, Oct 07, 2025 at 09:39:00PM +0000, Łukasz Bartosik wrote:
> From: Łukasz Bartosik <ukaszb@chromium.org>
>
> Add code which allows to set serial number of a DbC
> device through sysfs.
>
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> ---
> .../testing/sysfs-bus-pci-drivers-xhci_hcd | 13 +++++++
> drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++
> 2 files changed, 49 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> index fc82aa4e54b0..071688dbd969 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> @@ -85,3 +85,16 @@ Description:
> up to 5000. The default value is 64 ms.
> This polling interval is used while DbC is enabled but has no
> active data transfers.
> +
> +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iSerial
> +Date: October 2025
> +Contact: Łukasz Bartosik <ukaszb@chromium.org>
> +Description:
> + The dbc_iSerial attribute allows to change the iSerial field
> + presented in the USB device descriptor by xhci debug device.
> + Value can only be changed while debug capability (DbC) is in
> + disabled state to prevent USB device descriptor change while
> + connected to a USB host.
> + The default value is "0001".
> + The field length can be from 1 to 63 characters.
> +
> diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> index c2fecaffd6f3..7ad83548ba4d 100644
> --- a/drivers/usb/host/xhci-dbgcap.c
> +++ b/drivers/usb/host/xhci-dbgcap.c
> @@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
> return size;
> }
>
> +static ssize_t dbc_iSerial_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> + struct xhci_dbc *dbc = xhci->dbc;
> +
> + return sysfs_emit(buf, "%s\n", dbc->str.serial);
> +}
> +
> +static ssize_t dbc_iSerial_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t size)
> +{
> + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> + struct xhci_dbc *dbc = xhci->dbc;
> + size_t len;
> +
> + if (dbc->state != DS_DISABLED)
> + return -EBUSY;
> +
> + len = strcspn(buf, "\n");
So you are requiring the \n to be there? Why? What tool will write it?
You don't document this in up in the documentation :)
> + if (!len)
> + return -EINVAL;
> +
> + if (len > USB_MAX_STRING_LEN/2)
> + return -E2BIG;
> +
> + memcpy(dbc->str.serial, buf, len);
> + dbc->str.serial[len] = '\0';
As you know that buf is zero terminated, you can do a strcpy instead of
this two-step process. Ah, but that \n character, why not just zap it
out if it is present?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 2/4] xhci: dbc: allow to set serial number through sysfs
2025-10-08 11:20 ` Greg Kroah-Hartman
@ 2025-10-08 21:14 ` Łukasz Bartosik
0 siblings, 0 replies; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-08 21:14 UTC (permalink / raw)
To: Greg Kroah-Hartman; +Cc: Mathias Nyman, linux-usb
On Wed, Oct 8, 2025 at 1:20 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Tue, Oct 07, 2025 at 09:39:00PM +0000, Łukasz Bartosik wrote:
> > From: Łukasz Bartosik <ukaszb@chromium.org>
> >
> > Add code which allows to set serial number of a DbC
> > device through sysfs.
> >
> > Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> > ---
> > .../testing/sysfs-bus-pci-drivers-xhci_hcd | 13 +++++++
> > drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++
> > 2 files changed, 49 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> > index fc82aa4e54b0..071688dbd969 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> > +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> > @@ -85,3 +85,16 @@ Description:
> > up to 5000. The default value is 64 ms.
> > This polling interval is used while DbC is enabled but has no
> > active data transfers.
> > +
> > +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iSerial
> > +Date: October 2025
> > +Contact: Łukasz Bartosik <ukaszb@chromium.org>
> > +Description:
> > + The dbc_iSerial attribute allows to change the iSerial field
> > + presented in the USB device descriptor by xhci debug device.
> > + Value can only be changed while debug capability (DbC) is in
> > + disabled state to prevent USB device descriptor change while
> > + connected to a USB host.
> > + The default value is "0001".
> > + The field length can be from 1 to 63 characters.
> > +
> > diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> > index c2fecaffd6f3..7ad83548ba4d 100644
> > --- a/drivers/usb/host/xhci-dbgcap.c
> > +++ b/drivers/usb/host/xhci-dbgcap.c
> > @@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
> > return size;
> > }
> >
> > +static ssize_t dbc_iSerial_show(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> > + struct xhci_dbc *dbc = xhci->dbc;
> > +
> > + return sysfs_emit(buf, "%s\n", dbc->str.serial);
> > +}
> > +
> > +static ssize_t dbc_iSerial_store(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf, size_t size)
> > +{
> > + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> > + struct xhci_dbc *dbc = xhci->dbc;
> > + size_t len;
> > +
> > + if (dbc->state != DS_DISABLED)
> > + return -EBUSY;
> > +
> > + len = strcspn(buf, "\n");
>
> So you are requiring the \n to be there? Why? What tool will write it?
I'm not requiring \n to be present. The purpose of this line is to
exclude \n from
being copied. These new fields accessible through sysfs (serial,
manufacturer, product) will be written by ChromeOS software stack.
> You don't document this in up in the documentation :)
>
I added the description of dbc_iSerial, dbc_iProduct and dbc_iManufacturer
to the sysfs-bus-pci-drivers-xhci_hcd.
What else would you like to see added there ?
> > + if (!len)
> > + return -EINVAL;
> > +
> > + if (len > USB_MAX_STRING_LEN/2)
> > + return -E2BIG;
> > +
> > + memcpy(dbc->str.serial, buf, len);
> > + dbc->str.serial[len] = '\0';
>
> As you know that buf is zero terminated, you can do a strcpy instead of
> this two-step process. Ah, but that \n character, why not just zap it
> out if it is present?
>
I could use strcpy however I want to get rid of \n if it is present.
Thanks,
Łukasz
> thanks,
>
> greg k-h
^ permalink raw reply [flat|nested] 16+ messages in thread
* [PATCH v2 3/4] xhci: dbc: allow to set product name through sysfs
2025-10-07 21:38 [PATCH v2 0/4] Enable to set DbC strings through sysfs Łukasz Bartosik
2025-10-07 21:38 ` [PATCH v2 1/4] xhci: dbc: prepare to expose " Łukasz Bartosik
2025-10-07 21:39 ` [PATCH v2 2/4] xhci: dbc: allow to set serial number " Łukasz Bartosik
@ 2025-10-07 21:39 ` Łukasz Bartosik
2025-10-13 9:01 ` Mathias Nyman
2025-10-07 21:39 ` [PATCH v2 4/4] xhci: dbc: allow to set manufacturer " Łukasz Bartosik
3 siblings, 1 reply; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-07 21:39 UTC (permalink / raw)
To: Mathias Nyman, Greg Kroah-Hartman; +Cc: linux-usb, Łukasz Bartosik
From: Łukasz Bartosik <ukaszb@chromium.org>
Add code which allows to set product name of a DbC
device through sysfs.
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
.../testing/sysfs-bus-pci-drivers-xhci_hcd | 11 ++++++
drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++
2 files changed, 47 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
index 071688dbd969..57ba37606f79 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -98,3 +98,14 @@ Description:
The default value is "0001".
The field length can be from 1 to 63 characters.
+What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iProduct
+Date: October 2025
+Contact: Łukasz Bartosik <ukaszb@chromium.org>
+Description:
+ The dbc_iProduct attribute allows to change the iProduct field
+ presented in the USB device descriptor by xhci debug device.
+ Value can only be changed while debug capability (DbC) is in
+ disabled state to prevent USB device descriptor change while
+ connected to a USB host.
+ The default value is "Linux USB Debug Target".
+ The field length can be from 1 to 63 characters.
diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index 7ad83548ba4d..bc782f6b533e 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
return size;
}
+static ssize_t dbc_iProduct_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+ struct xhci_dbc *dbc = xhci->dbc;
+
+ return sysfs_emit(buf, "%s\n", dbc->str.product);
+}
+
+static ssize_t dbc_iProduct_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+ struct xhci_dbc *dbc = xhci->dbc;
+ size_t len;
+
+ if (dbc->state != DS_DISABLED)
+ return -EBUSY;
+
+ len = strcspn(buf, "\n");
+ if (!len)
+ return -EINVAL;
+
+ if (len > USB_MAX_STRING_LEN/2)
+ return -E2BIG;
+
+ memcpy(dbc->str.product, buf, len);
+ dbc->str.product[len] = '\0';
+
+ return size;
+}
+
static ssize_t dbc_iSerial_show(struct device *dev,
struct device_attribute *attr,
char *buf)
@@ -1321,6 +1355,7 @@ static DEVICE_ATTR_RW(dbc);
static DEVICE_ATTR_RW(dbc_idVendor);
static DEVICE_ATTR_RW(dbc_idProduct);
static DEVICE_ATTR_RW(dbc_bcdDevice);
+static DEVICE_ATTR_RW(dbc_iProduct);
static DEVICE_ATTR_RW(dbc_iSerial);
static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
static DEVICE_ATTR_RW(dbc_poll_interval_ms);
@@ -1330,6 +1365,7 @@ static struct attribute *dbc_dev_attrs[] = {
&dev_attr_dbc_idVendor.attr,
&dev_attr_dbc_idProduct.attr,
&dev_attr_dbc_bcdDevice.attr,
+ &dev_attr_dbc_iProduct.attr,
&dev_attr_dbc_iSerial.attr,
&dev_attr_dbc_bInterfaceProtocol.attr,
&dev_attr_dbc_poll_interval_ms.attr,
--
2.51.0.710.ga91ca5db03-goog
^ permalink raw reply related [flat|nested] 16+ messages in thread* Re: [PATCH v2 3/4] xhci: dbc: allow to set product name through sysfs
2025-10-07 21:39 ` [PATCH v2 3/4] xhci: dbc: allow to set product name " Łukasz Bartosik
@ 2025-10-13 9:01 ` Mathias Nyman
2025-10-13 22:19 ` Łukasz Bartosik
0 siblings, 1 reply; 16+ messages in thread
From: Mathias Nyman @ 2025-10-13 9:01 UTC (permalink / raw)
To: Łukasz Bartosik, Mathias Nyman, Greg Kroah-Hartman; +Cc: linux-usb
On 10/8/25 00:39, Łukasz Bartosik wrote:
> From: Łukasz Bartosik <ukaszb@chromium.org>
>
> Add code which allows to set product name of a DbC
> device through sysfs.
>
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> ---
> .../testing/sysfs-bus-pci-drivers-xhci_hcd | 11 ++++++
> drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++
> 2 files changed, 47 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> index 071688dbd969..57ba37606f79 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> @@ -98,3 +98,14 @@ Description:
> The default value is "0001".
> The field length can be from 1 to 63 characters.
>
> +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iProduct
> +Date: October 2025
> +Contact: Łukasz Bartosik <ukaszb@chromium.org>
> +Description:
> + The dbc_iProduct attribute allows to change the iProduct field
> + presented in the USB device descriptor by xhci debug device.
> + Value can only be changed while debug capability (DbC) is in
> + disabled state to prevent USB device descriptor change while
> + connected to a USB host.
> + The default value is "Linux USB Debug Target".
> + The field length can be from 1 to 63 characters.
> diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> index 7ad83548ba4d..bc782f6b533e 100644
> --- a/drivers/usb/host/xhci-dbgcap.c
> +++ b/drivers/usb/host/xhci-dbgcap.c
> @@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
> return size;
> }
>
> +static ssize_t dbc_iProduct_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> + struct xhci_dbc *dbc = xhci->dbc;
> +
> + return sysfs_emit(buf, "%s\n", dbc->str.product);
> +}
> +
> +static ssize_t dbc_iProduct_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t size)
> +{
> + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> + struct xhci_dbc *dbc = xhci->dbc;
> + size_t len;
> +
> + if (dbc->state != DS_DISABLED)
> + return -EBUSY;
> +
> + len = strcspn(buf, "\n");
> + if (!len)
> + return -EINVAL;
> +
> + if (len > USB_MAX_STRING_LEN/2)
> + return -E2BIG;
> +
> + memcpy(dbc->str.product, buf, len);
> + dbc->str.product[len] = '\0';
> +
> + return size;
> +}
> +
> static ssize_t dbc_iSerial_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> @@ -1321,6 +1355,7 @@ static DEVICE_ATTR_RW(dbc);
> static DEVICE_ATTR_RW(dbc_idVendor);
> static DEVICE_ATTR_RW(dbc_idProduct);
> static DEVICE_ATTR_RW(dbc_bcdDevice);
> +static DEVICE_ATTR_RW(dbc_iProduct);
> static DEVICE_ATTR_RW(dbc_iSerial);
> static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
> static DEVICE_ATTR_RW(dbc_poll_interval_ms);
> @@ -1330,6 +1365,7 @@ static struct attribute *dbc_dev_attrs[] = {
> &dev_attr_dbc_idVendor.attr,
> &dev_attr_dbc_idProduct.attr,
> &dev_attr_dbc_bcdDevice.attr,
> + &dev_attr_dbc_iProduct.attr,
Small naming thing again.
"dbc_idProduct" and dbc_iProduct" are a bit too similar.
Usb core uses "product" and "manufacturer" sysfs entries to show these strings.
I think dbc should use similar "dbc_product" and "dbc_manufacturer" naming.
the "iProduct" is a byte in device descriptor telling the index of the product string
descriptor.
Thanks
Mathias
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 3/4] xhci: dbc: allow to set product name through sysfs
2025-10-13 9:01 ` Mathias Nyman
@ 2025-10-13 22:19 ` Łukasz Bartosik
2025-10-13 22:27 ` Mathias Nyman
0 siblings, 1 reply; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-13 22:19 UTC (permalink / raw)
To: Mathias Nyman; +Cc: Mathias Nyman, Greg Kroah-Hartman, linux-usb
On Mon, Oct 13, 2025 at 11:01 AM Mathias Nyman
<mathias.nyman@linux.intel.com> wrote:
>
> On 10/8/25 00:39, Łukasz Bartosik wrote:
> > From: Łukasz Bartosik <ukaszb@chromium.org>
> >
> > Add code which allows to set product name of a DbC
> > device through sysfs.
> >
> > Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> > ---
> > .../testing/sysfs-bus-pci-drivers-xhci_hcd | 11 ++++++
> > drivers/usb/host/xhci-dbgcap.c | 36 +++++++++++++++++++
> > 2 files changed, 47 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> > index 071688dbd969..57ba37606f79 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> > +++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
> > @@ -98,3 +98,14 @@ Description:
> > The default value is "0001".
> > The field length can be from 1 to 63 characters.
> >
> > +What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_iProduct
> > +Date: October 2025
> > +Contact: Łukasz Bartosik <ukaszb@chromium.org>
> > +Description:
> > + The dbc_iProduct attribute allows to change the iProduct field
> > + presented in the USB device descriptor by xhci debug device.
> > + Value can only be changed while debug capability (DbC) is in
> > + disabled state to prevent USB device descriptor change while
> > + connected to a USB host.
> > + The default value is "Linux USB Debug Target".
> > + The field length can be from 1 to 63 characters.
> > diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> > index 7ad83548ba4d..bc782f6b533e 100644
> > --- a/drivers/usb/host/xhci-dbgcap.c
> > +++ b/drivers/usb/host/xhci-dbgcap.c
> > @@ -1200,6 +1200,40 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
> > return size;
> > }
> >
> > +static ssize_t dbc_iProduct_show(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> > + struct xhci_dbc *dbc = xhci->dbc;
> > +
> > + return sysfs_emit(buf, "%s\n", dbc->str.product);
> > +}
> > +
> > +static ssize_t dbc_iProduct_store(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf, size_t size)
> > +{
> > + struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
> > + struct xhci_dbc *dbc = xhci->dbc;
> > + size_t len;
> > +
> > + if (dbc->state != DS_DISABLED)
> > + return -EBUSY;
> > +
> > + len = strcspn(buf, "\n");
> > + if (!len)
> > + return -EINVAL;
> > +
> > + if (len > USB_MAX_STRING_LEN/2)
> > + return -E2BIG;
> > +
> > + memcpy(dbc->str.product, buf, len);
> > + dbc->str.product[len] = '\0';
> > +
> > + return size;
> > +}
> > +
> > static ssize_t dbc_iSerial_show(struct device *dev,
> > struct device_attribute *attr,
> > char *buf)
> > @@ -1321,6 +1355,7 @@ static DEVICE_ATTR_RW(dbc);
> > static DEVICE_ATTR_RW(dbc_idVendor);
> > static DEVICE_ATTR_RW(dbc_idProduct);
> > static DEVICE_ATTR_RW(dbc_bcdDevice);
> > +static DEVICE_ATTR_RW(dbc_iProduct);
> > static DEVICE_ATTR_RW(dbc_iSerial);
> > static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
> > static DEVICE_ATTR_RW(dbc_poll_interval_ms);
> > @@ -1330,6 +1365,7 @@ static struct attribute *dbc_dev_attrs[] = {
> > &dev_attr_dbc_idVendor.attr,
> > &dev_attr_dbc_idProduct.attr,
> > &dev_attr_dbc_bcdDevice.attr,
> > + &dev_attr_dbc_iProduct.attr,
>
> Small naming thing again.
>
> "dbc_idProduct" and dbc_iProduct" are a bit too similar.
>
> Usb core uses "product" and "manufacturer" sysfs entries to show these strings.
> I think dbc should use similar "dbc_product" and "dbc_manufacturer" naming.
>
I will rename it in patchset v3.
> the "iProduct" is a byte in device descriptor telling the index of the product string
> descriptor.
>
The same applies to iSerial then. Should I rename it to "dbc_serial" as well ?
Thanks,
Łukasz
> Thanks
> Mathias
>
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH v2 3/4] xhci: dbc: allow to set product name through sysfs
2025-10-13 22:19 ` Łukasz Bartosik
@ 2025-10-13 22:27 ` Mathias Nyman
0 siblings, 0 replies; 16+ messages in thread
From: Mathias Nyman @ 2025-10-13 22:27 UTC (permalink / raw)
To: Łukasz Bartosik; +Cc: Mathias Nyman, Greg Kroah-Hartman, linux-usb
On 10/14/25 01:19, Łukasz Bartosik wrote:
> On Mon, Oct 13, 2025 at 11:01 AM Mathias Nyman
> <mathias.nyman@linux.intel.com> wrote:
>>
>> On 10/8/25 00:39, Łukasz Bartosik wrote:
>>> From: Łukasz Bartosik <ukaszb@chromium.org>
>>>
>>> Add code which allows to set product name of a DbC
>>> device through sysfs.
>>>
>>> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
>>> ---
>>> @@ -1321,6 +1355,7 @@ static DEVICE_ATTR_RW(dbc);
>>> static DEVICE_ATTR_RW(dbc_idVendor);
>>> static DEVICE_ATTR_RW(dbc_idProduct);
>>> static DEVICE_ATTR_RW(dbc_bcdDevice);
>>> +static DEVICE_ATTR_RW(dbc_iProduct);
>>> static DEVICE_ATTR_RW(dbc_iSerial);
>>> static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
>>> static DEVICE_ATTR_RW(dbc_poll_interval_ms);
>>> @@ -1330,6 +1365,7 @@ static struct attribute *dbc_dev_attrs[] = {
>>> &dev_attr_dbc_idVendor.attr,
>>> &dev_attr_dbc_idProduct.attr,
>>> &dev_attr_dbc_bcdDevice.attr,
>>> + &dev_attr_dbc_iProduct.attr,
>>
>> Small naming thing again.
>>
>> "dbc_idProduct" and dbc_iProduct" are a bit too similar.
>>
>> Usb core uses "product" and "manufacturer" sysfs entries to show these strings.
>> I think dbc should use similar "dbc_product" and "dbc_manufacturer" naming.
>>
>
> I will rename it in patchset v3.
>
>> the "iProduct" is a byte in device descriptor telling the index of the product string
>> descriptor.
>>
>
> The same applies to iSerial then. Should I rename it to "dbc_serial" as well ?
I think that would work better yes
Thanks
Mathias
^ permalink raw reply [flat|nested] 16+ messages in thread
* [PATCH v2 4/4] xhci: dbc: allow to set manufacturer name through sysfs
2025-10-07 21:38 [PATCH v2 0/4] Enable to set DbC strings through sysfs Łukasz Bartosik
` (2 preceding siblings ...)
2025-10-07 21:39 ` [PATCH v2 3/4] xhci: dbc: allow to set product name " Łukasz Bartosik
@ 2025-10-07 21:39 ` Łukasz Bartosik
3 siblings, 0 replies; 16+ messages in thread
From: Łukasz Bartosik @ 2025-10-07 21:39 UTC (permalink / raw)
To: Mathias Nyman, Greg Kroah-Hartman; +Cc: linux-usb, Łukasz Bartosik
From: Łukasz Bartosik <ukaszb@chromium.org>
Add code which allows to set manufacturer name of a DbC
device through sysfs.
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
.../testing/sysfs-bus-pci-drivers-xhci_hcd | 12 +++++++
drivers/usb/host/xhci-dbgcap.c | 35 +++++++++++++++++++
2 files changed, 47 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
index 57ba37606f79..26ca6a870e44 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -109,3 +109,15 @@ Description:
connected to a USB host.
The default value is "Linux USB Debug Target".
The field length can be from 1 to 63 characters.
+
+What: /sys/bus/pci/drivers/xhci_hcd/.../dbc_Manufacturer
+Date: October 2025
+Contact: Łukasz Bartosik <ukaszb@chromium.org>
+Description:
+ The dbc_iManufacturer attribute allows to change the iManufacturer
+ field presented in the USB device descriptor by xhci debug device.
+ Value can only be changed while debug capability (DbC) is in
+ disabled state to prevent USB device descriptor change while
+ connected to a USB host.
+ The default value is "Linux Foundation".
+ The field length can be from 1 to 63 characters.
diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
index bc782f6b533e..badd20f2dcd9 100644
--- a/drivers/usb/host/xhci-dbgcap.c
+++ b/drivers/usb/host/xhci-dbgcap.c
@@ -1200,6 +1200,39 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
return size;
}
+static ssize_t dbc_iManufacturer_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+ struct xhci_dbc *dbc = xhci->dbc;
+
+ return sysfs_emit(buf, "%s\n", dbc->str.manufacturer);
+}
+
+static ssize_t dbc_iManufacturer_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct xhci_hcd *xhci = hcd_to_xhci(dev_get_drvdata(dev));
+ struct xhci_dbc *dbc = xhci->dbc;
+ size_t len;
+
+ if (dbc->state != DS_DISABLED)
+ return -EBUSY;
+
+ len = strcspn(buf, "\n");
+ if (!len)
+ return -EINVAL;
+
+ if (len > USB_MAX_STRING_LEN/2)
+ return -E2BIG;
+
+ memcpy(dbc->str.manufacturer, buf, len);
+ dbc->str.manufacturer[len] = '\0';
+
+ return size;
+}
static ssize_t dbc_iProduct_show(struct device *dev,
struct device_attribute *attr,
char *buf)
@@ -1355,6 +1388,7 @@ static DEVICE_ATTR_RW(dbc);
static DEVICE_ATTR_RW(dbc_idVendor);
static DEVICE_ATTR_RW(dbc_idProduct);
static DEVICE_ATTR_RW(dbc_bcdDevice);
+static DEVICE_ATTR_RW(dbc_iManufacturer);
static DEVICE_ATTR_RW(dbc_iProduct);
static DEVICE_ATTR_RW(dbc_iSerial);
static DEVICE_ATTR_RW(dbc_bInterfaceProtocol);
@@ -1365,6 +1399,7 @@ static struct attribute *dbc_dev_attrs[] = {
&dev_attr_dbc_idVendor.attr,
&dev_attr_dbc_idProduct.attr,
&dev_attr_dbc_bcdDevice.attr,
+ &dev_attr_dbc_iManufacturer.attr,
&dev_attr_dbc_iProduct.attr,
&dev_attr_dbc_iSerial.attr,
&dev_attr_dbc_bInterfaceProtocol.attr,
--
2.51.0.710.ga91ca5db03-goog
^ permalink raw reply related [flat|nested] 16+ messages in thread