From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: zhenwei pi <pizhenwei@bytedance.com>,
peter.maydell@linaro.org, richard.henderson@linaro.org,
kraxel@redhat.com, eblake@redhat.com, pbonzini@redhat.com
Cc: qemu-devel@nongnu.org
Subject: Re: [PATCH 4/5] usb: allow max 8192 bytes for desc
Date: Tue, 11 Jan 2022 14:00:30 +0100 [thread overview]
Message-ID: <0f5fac84-26f1-7304-6575-c3944f47cb7c@amsat.org> (raw)
In-Reply-To: <708c4228-d123-b403-09ff-b7d75bf1bba4@bytedance.com>
On 1/5/22 08:25, zhenwei pi wrote:
>
> On 1/4/22 11:22 PM, Philippe Mathieu-Daudé wrote:
>> On 27/12/21 15:27, zhenwei pi wrote:
>>> A device of USB video class usually uses larger desc structure, so
>>> use larger buffer to avoid failure.
>>>
>>> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
>>> ---
>>> hw/usb/desc.c | 15 ++++++++-------
>>> hw/usb/desc.h | 1 +
>>> 2 files changed, 9 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/hw/usb/desc.c b/hw/usb/desc.c
>>> index 8b6eaea407..7f6cc2f99b 100644
>>> --- a/hw/usb/desc.c
>>> +++ b/hw/usb/desc.c
>>> @@ -632,7 +632,8 @@ int usb_desc_get_descriptor(USBDevice *dev,
>>> USBPacket *p,
>>> bool msos = (dev->flags & (1 << USB_DEV_FLAG_MSOS_DESC_IN_USE));
>>> const USBDesc *desc = usb_device_get_usb_desc(dev);
>>> const USBDescDevice *other_dev;
>>> - uint8_t buf[256];
>>> + size_t buflen = USB_DESC_MAX_LEN;
>>> + g_autofree uint8_t *buf = g_malloc(buflen);
>>
>> Do we want to have a per-device desc_size (in USBDevice, default to
>> 256, video devices set it to 8K)?
>>
>> How "hot" is this path? Could we keep 8K on the stack?
>>
> It's an unlikely code path:
> 1, During guest startup, guest tries to probe device.
> 2, run 'lsusb' command in guest
If you have to respin, do you mind adding this 3 lines
in the description? Anyhow:
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
next prev parent reply other threads:[~2022-01-11 13:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-27 14:27 [PATCH 0/5] Introduce camera subsystem and USB video device zhenwei pi
2021-12-27 14:27 ` [PATCH 1/5] camera: Introduce camera subsystem and builtin driver zhenwei pi
2021-12-27 14:27 ` [PATCH 2/5] camera: v4l2: Introduce v4l2 camera driver zhenwei pi
2021-12-27 14:27 ` [PATCH 3/5] usb: Introduce video&mescellaneous zhenwei pi
2021-12-27 14:27 ` [PATCH 4/5] usb: allow max 8192 bytes for desc zhenwei pi
2022-01-04 15:22 ` Philippe Mathieu-Daudé
2022-01-05 7:25 ` zhenwei pi
2022-01-11 13:00 ` Philippe Mathieu-Daudé [this message]
2022-01-11 12:37 ` Daniel P. Berrangé
2021-12-27 14:27 ` [PATCH 5/5] usb-video: Introduce USB video class zhenwei pi
2022-01-04 13:39 ` [PATCH 0/5] Introduce camera subsystem and USB video device Daniel P. Berrangé
2022-01-05 7:03 ` zhenwei pi
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