From: Thomas Gleixner <tglx@linutronix.de>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Johan Hovold <johan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org,
Thomas Winischhofer <thomas@winischhofer.net>,
"Ahmed S. Darwish" <a.darwish@linutronix.de>,
Mathias Nyman <mathias.nyman@intel.com>,
Valentina Manea <valentina.manea.m@gmail.com>,
Shuah Khan <shuah@kernel.org>,
linux-omap@vger.kernel.org, Kukjin Kim <kgene@kernel.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org,
Felipe Balbi <balbi@kernel.org>,
Duncan Sands <duncan.sands@free.fr>
Subject: Re: [patch 03/12] USB: serial: keyspan_pda: Consolidate room query
Date: Wed, 14 Oct 2020 18:17:51 +0200 [thread overview]
Message-ID: <87ft6gbx3k.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201014161433.GB712494@rowland.harvard.edu>
On Wed, Oct 14 2020 at 12:14, Alan Stern wrote:
> On Wed, Oct 14, 2020 at 04:52:18PM +0200, Thomas Gleixner wrote:
>> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>>
>> Having two copies of the same code doesn't make the code more readable and
>> allocating a buffer of 1 byte for a synchronous operation is a pointless
>> exercise.
>
> Not so. In fact, it is required, because a portion of a structure
> cannot be mapped for DMA unless it is aligned at a cache line boundary.
>
>> Add a byte buffer to struct keyspan_pda_private which can be used
>> instead. The buffer is only used in open() and tty->write().
>
> This won't work.
Ok.
>> + res = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
>> + 6, /* write_room */
>> + USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_IN,
>> + 0, /* value */
>> + 0, /* index */
>> + &priv->query_buf,
>> + 1,
>> + 2000);
>
> Instead, consider using the new usb_control_msg_recv() API. But it
> might be better to allocate the buffer once and for all.
Let me have a look.
Thanks,
tglx
next prev parent reply other threads:[~2020-10-14 16:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 14:52 [patch 00/12] UBS: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
2020-10-14 14:52 ` [patch 01/12] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
2020-10-14 14:52 ` [patch 02/12] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
2020-10-14 14:52 ` [patch 03/12] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
2020-10-14 16:14 ` Alan Stern
2020-10-14 16:17 ` Thomas Gleixner [this message]
2020-10-14 16:27 ` Sebastian Andrzej Siewior
2020-10-14 16:34 ` Alan Stern
2020-10-14 16:44 ` Sebastian Andrzej Siewior
2020-10-14 14:52 ` [patch 04/12] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
2020-10-14 14:52 ` [patch 05/12] usb: xhci: Remove in_interrupt() checks Thomas Gleixner
2020-10-23 13:38 ` Mathias Nyman
2020-10-14 14:52 ` [patch 06/12] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
2020-10-14 14:52 ` [patch 07/12] usbip: Remove in_interrupt() check Thomas Gleixner
2020-10-14 15:45 ` Shuah Khan
2020-10-14 14:52 ` [patch 08/12] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
2020-10-14 15:24 ` Krzysztof Kozlowski
2020-10-14 16:20 ` Alan Stern
2020-10-14 14:52 ` [patch 09/12] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments Thomas Gleixner
2020-10-14 14:52 ` [patch 10/12] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
2020-10-14 16:22 ` Alan Stern
2020-10-14 14:52 ` [patch 11/12] usb: core: Replace in_interrupt() in comments Thomas Gleixner
2020-10-14 16:27 ` Alan Stern
2020-10-14 16:41 ` Sebastian Andrzej Siewior
2020-10-14 18:13 ` Alan Stern
2020-10-14 14:52 ` [patch 12/12] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
2020-10-23 8:01 ` [patch 00/12] UBS: Cleanup in_interupt/in_irq/in_atomic() usage Pavel Machek
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