From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kumar Gala Subject: Re: [PATCH] Make the Startech UART detection 'more correct'. Date: Wed, 24 Sep 2003 17:40:04 -0500 Sender: linux-kernel-owner@vger.kernel.org Message-ID: <0A8F6030-EEE0-11D7-AA35-000393DBC2E8@motorola.com> References: <20030909235153.GB4559@ip68-0-152-218.tc.ph.cox.net> Mime-Version: 1.0 (Apple Message framework v552) Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20030909235153.GB4559@ip68-0-152-218.tc.ph.cox.net> To: tytso@mit.edu Cc: kernel Mailing List , linux-serial@vger.kernel.org, gallen@arlut.utexas.edu, Tom Rini List-Id: linux-serial@vger.kernel.org I was wondering what the status of this patch was for the 2.4 side? thanks - kumar On Tuesday, September 9, 2003, at 06:51 PM, Tom Rini wrote: > On Tue, Sep 09, 2003 at 05:18:59PM +0100, Russell King wrote: > >> On Mon, Sep 08, 2003 at 01:54:31PM -0700, Tom Rini wrote: >>> Hello. The following patches (vs 2.4 and 2.6) make the Startech UART >>> detection 'more correct' The problem is that on with the Motorola >>> MPC82xx line (8245 for example) it has an internal DUART that it >>> claims >>> to be PC16550D compatible, and it has an additional EFR (Enhanced >>> Feature Register) at offset 0x2, like on the Startech UARTS. >>> However, >>> it is not a Startech, and when it's detected as such, FIFOs don't >>> work. >>> The fix for this is that the Startech UARTs have a 32 byte FIFO [1] >>> and >>> the MPC82xx DUARTs have a 16-byte FIFO [2], to check that the FIFO >>> size >>> is correct for a Startech. >> >> size_fifo() is claimed to be unreliable at detecting the FIFO size, >> so I don't feel safe about using it here. >> >> I'd suggest something like: >> >> serial_outp(port, UART_LCR, UART_LCR_DLAB); >> efr = serial_in(port, UART_EFR); >> if ((efr & 0xfc) == 0) { >> serial_out(port, UART_EFR, 0xac | (efr & 3)); >> /* if top 6 bits return zero, its motorola */ >> if (serial_in(port, UART_EFR) == (efr & 3)) { >> /* motorola port */ >> } else { >> /* ST16C650V1 port */ >> } >> /* restore old value */ >> serial_outb(port, UART_EFR, efr); >> } > > Okay, from Kumar Gala (cc'ed) I've got the following patch for 2.4: > ===== drivers/char/serial.c 1.34 vs edited ===== > --- 1.34/drivers/char/serial.c Sun Jul 6 22:33:28 2003 > +++ edited/drivers/char/serial.c Tue Sep 9 16:50:22 2003 > @@ -3741,7 +3741,10 @@ > /* Check for Startech UART's */ > serial_outp(info, UART_LCR, UART_LCR_DLAB); > if (serial_in(info, UART_EFR) == 0) { > - state->type = PORT_16650; > + serial_outp(info, UART_EFR, 0xA8); > + if (serial_in(info, UART_EFR) != 0) > + state->type = PORT_16650; > + serial_outp(info, UART_EFR, 0); > } else { > serial_outp(info, UART_LCR, 0xBF); > if (serial_in(info, UART_EFR) == 0) > > And I forward ported this up to 2.6 as: > ===== drivers/serial/8250.c 1.36 vs edited ===== > --- 1.36/drivers/serial/8250.c Tue Sep 9 07:22:12 2003 > +++ edited/drivers/serial/8250.c Tue Sep 9 16:49:07 2003 > @@ -469,8 +469,13 @@ > */ > serial_outp(up, UART_LCR, UART_LCR_DLAB); > if (serial_in(up, UART_EFR) == 0) { > - DEBUG_AUTOCONF("EFRv1 "); > - up->port.type = PORT_16650; > + serial_outp(up, UART_EFR, 0xA8); > + if (serial_in(up, UART_EFR) != 0) { > + DEBUG_AUTOCONF("EFRv1 "); > + up->port.type = PORT_16650; > + } else > + DEBUG_AUTOCONF("Motorola 8xxx DUART "); > + serial_outp(up, UART_EFR, 0); > return; > } > > Better? > > -- > Tom Rini > http://gate.crashing.org/~trini/ >